An Account of Meteorological Observations in Four Balloon Ascents, Made under the Direction of the Kew Observatory Committee of the British Association for the Advancement of Science

XII. An Account of Meteorological Observations in Four Balloon Ascents, made under the direction of the Kew Observatory Committee of the British Association for the Advancement of Science. By John Welsh, Esq. Communicated by Colonel Sabine, R.A., Treas. and V.P.R.S., by the request of the Council of the British Association for the Advancement of Science. Received April 27,—Read May 26, 1853. In July 1852, the Committee of the Kew Observatory resolved to institute a series of balloon ascents, with the view of investigating such meteorological and physical phenomena as require the presence of an observer at a great height in the atmosphere. The arrangements made for carrying out this resolution have been stated by the Committee in their report to the Council of the British Association, a short account being at the same time given of some of the results derived from the ascents already made. Having been to a great extent entrusted by the Committee with the conduct of the observations and with the instrumental arrangements, I now, at their request, proceed to give a more detailed statement of the mode in which the experiments have been made, and of such results as may most readily be deduced from the observations recorded in the ascents. The object to which especial attention was devoted, was the determination of the temperature and hygrometric condition of the air at different elevations above the earth's surface. Besides this, the observers were furnished with the means of procuring specimens of the air at different heights for the purpose of analysis, and of examining, if opportunity offered, whether the light reflected from the upper surface of the clouds was polarized. § 1. Instruments and Apparatus. The instruments required for the investigations contemplated were—a barometer; dry and wet thermometers; an aspirator; Regnault's condensing hygrometer; Daniell's dew-point hygrometer; a polariscope; and glass tubes, furnished with MDCCCLIII. stopcocks, from which the air had been exhausted. All the instruments which were at all liable to accident were supplied in duplicate. The construction of the meteorological instruments was confided by the Committee to Mr. P. Adie of London, under my own general superintendence. They were executed by him in a very satisfactory manner, having been made with much accuracy and with an anxious wish to promote the success of the experiments; many of the mechanical arrangements for the convenience of observation having also been devised by him. Barometers.—The barometer employed was of the siphon form, on the construction generally known as Gay-Lussac's. The tube was affixed to a brass scale in much the same way as a thermometer is attached to its scale. The brass scale was fixed within a stout rosewood frame furnished with a door which could be closed during carriage. The diameter of the tube was 0·25 inch. The graduation was made from the middle point upwards and downwards; each division being $\frac{1}{20}$th of an inch long, but representing twice that value; so that an observation of either branch of the siphon would give the length of the column of mercury, subject to a correction for inequality of the tube and error in the position of the zero-point of the scale. A complete observation of the instrument required however readings of both branches of the siphon, the true height of the mercury being the mean of the two. In order to facilitate rapidity of observation, verniers were dispensed with, the height of the mercury being merely estimated with reference to the scale placed behind it, just as if it had been a thermometer of large calibre. As it would have been nearly impossible to obtain in the car of the balloon a complete reading of both branches of the siphon for each observation, the corrections to the readings of the upper branch alone were previously obtained, throughout the anticipated range of the mercury, by the help of a large vacuum apparatus at the Kew Observatory, which has been employed in the pendulum experiments of Colonel Sabine and Professor Stokes. The barometers having been suspended within the receiver, the air was exhausted by about half an inch of pressure at a time, and readings taken from which tables of corrections were computed for different heights of the mercury. These corrections have been applied to all the observations. The difference between the indications of the siphon barometers and those of the Kew standard was also observed: both barometers were found to read 0·025 inch higher than the standard. It was found, by intercomparisons made last year, that the standard barometer at the Royal Observatory, Greenwich, reads lower than the Kew standard by 0·003 inch. The balloon barometers thus read 0·028 inch higher than the Greenwich standard; and, as that barometer has been generally referred to in the computations of height, the equation $+0·028$ has been applied to the terrestrial observations to render them comparable with those of the balloon barometers. Each barometer was provided with a thermometer to indicate the temperature of the mercury. In order to obtain this temperature more accurately, the bulb of the thermometer (which was cylindrical, about 1$\frac{1}{2}$ inch long and $\frac{1}{8}$th of an inch diameter) was immersed in mercury contained in a tube of the same diameter as that of the barometer. The necessity for this precaution was found to be great, as very large differences sometimes existed between the temperature of the air thermometer and that of the mercury. **Dry and Wet Thermometers.**—Two pairs of dry and wet thermometers were employed. One pair was mounted with the bulbs protected from radiation by a double conical shade, having highly polished silver surfaces, open at top and bottom to allow the circulation of the air. The inner shade was 2 inches high, $1\frac{3}{4}$ inch wide at the lower, and half an inch at the upper end; the outer shade was also 2 inches high, $2\frac{3}{4}$ inches wide at the lower, and $1\frac{3}{8}$ inch at the upper end*. Both thermometers were furnished with shades exactly similar; the bulbs being thus in the same circumstances, and completely protected from direct radiation. The thermometers were supported, $3\frac{1}{2}$ inches apart, by the arms of a light brass frame, also with a polished silver surface. A small brass cistern was fixed near the wet thermometer, from which water was conveyed to the bulb by a conducting string of floss silk; when however the temperature fell below the freezing-point, the string was cut away and the bulb occasionally dipped in water. As it was of essential importance that the thermometers should acquire with the utmost possible rapidity the temperature of the surrounding air, an arrangement was made, in connection with the second pair of dry and wet thermometers, for producing artificially a more rapid current over the bulbs than they would be exposed to by the mere vertical motion of the balloon. It was also thought desirable to avoid any tendency to a stagnation of the vapour of water in the neighbourhood of the wet bulb owing to the want of a sufficient circulation of air to carry it off, as might be the case when the balloon was nearly stationary or moving very slowly. An increased velocity in the circulation of the air would also tend to remove the effects of radiation, if the thermometers were not already sufficiently protected by the shades. With these objects the following contrivance was adopted. The thermometers were fixed vertically with their bulbs enclosed in two tubes placed side by side, and connected with each other by a cross tube joining their upper ends; these tubes having silver surfaces, and being further protected by a silver shade of the same dimensions as the outer shade of the other pair of thermometers. The first tube, in which was the bulb of the dry thermometer, had at its lower end a communication with the air: by means of an aspirator a current was produced from this opening, upwards over the dry bulb, then passing, by the communication at the top, into the second tube down which it moved over the wet bulb, leaving it by an opening connected by a flexible pipe with the aspirator. By this means, the temperature of the air was determined in its passage over the dry bulb, and afterwards its hygrometric condition on coming in contact with the wet; the vapour of water formed at the latter being carried off immediately into the aspirator. The whole distance which the air had to * It might have been preferable to make the inner shade cylindrical instead of conical, as the air would have circulated more freely. travel, between its entrance into the tubes and its leaving the wet thermometer, was about 4 inches: the diameter of the tubes enclosing the bulbs was 0·4 inch, and that of the connecting tube 0·25 inch. The aspirator was a cylindrical bellows; the valves being so arranged that, when the aspirator was forced open, the air could only enter it by passing over the thermometers: it was worked by attaching a weight to the lower end which pulled it open, the upper end being fixed; when it had opened to nearly its full extent, it was closed by means of a cord passing over pulleys and drawn up by the hand; a large valve allowing the air to escape rapidly from the aspirator as it was closed, and a second valve preventing the air from being driven backwards over the thermometers. Care was taken, in the construction of the different parts, that the aperture of the tubes should not be smaller between the thermometers and the external air, than between them and the aspirator; otherwise the air might, by undergoing a certain degree of expansion, have come in contact with the bulbs in different conditions with respect to temperature and capacity for moisture from those of the external air. This was guarded against by applying a stopcock near the aspirator, whose aperture was sufficiently small. A second flexible tube, with a stopcock, connected the aspirator with Regnault's hygrometer; so that the same aspirator might be used simultaneously for both instruments. Two different sizes of aspirator were used in the different ascents; the one being 12 inches diameter, and extending to about 18 inches, occupying about 1½ minute in its descent; the other was 9 inches diameter, extending to 12 inches in 30 to 40 seconds. This was sufficient to produce a current of air over the bulbs at the rate of 12 to 14 feet in a second; the vertical velocity of the balloon seldom exceeding 4 or 5 feet. The thermometers employed were of great sensibility; the bulbs being cylindrical, the diameter not exceeding ¼th of an inch, and the length varying from a half to three-quarters of an inch. The length of one degree of the scale was from ¼th to ½th of an inch, so that they could readily be read by estimation to 0°·1. The graduation extended to 30° or 40° below zero of Fahrenheit. The scales of those used in the first ascent were of brass, but afterwards of ivory, in order to render the column of mercury more visible. The errors of all the thermometers were determined throughout the scale, from about 0° to 70°, by comparison with standards at the Kew Observatory; the comparisons below the freezing-point being made in mixtures of ice and salt. The corrections have been applied to all the readings. These thermometers were found to acquire the temperature of the air very rapidly: when heated 20° above the temperature of the air, and allowed to cool at rest in a confined room, they returned to within 0°·5 of the previous reading in about 100 seconds; when gently fanned, by being carried through the room at the rate of 5 or 6 feet in a second, they returned to within 0°·5 in 40 seconds; when under the action of the aspirator they returned to within 0°·5 in 30 seconds, and exactly to the original reading in 45 seconds. Any correction on account of sluggishness in the thermometers must thus be very small: this is shown by the observations of October 21, when the descent took place with about the same velocity as the ascent, and observations were continued to within 3000 feet of the earth. The differences of temperature at the same height are scarcely appreciable, and even frequently in the opposite direction from what would result from insensibility in the thermometer. A few observations were taken during the descent on August 17, which, when compared with those made at the same height in the ascent, show a difference of about four degrees. The rapidity of the descent was on that occasion about twice as great as that of the ascent, which was also considerable, and the thermometers were not under aspiration. The protection from radiation has been examined by observing the thermometers within a room when alternately exposed to strong sunshine and shade—the effect upon the aspirated thermometers did not exceed $1^\circ$-5: in the open air, and with a gentle breeze, the effect was considerably less. The effect upon the free thermometer appeared to be greater; and the difference between its indications and those of the aspirated thermometer during some of the ascents is probably to be ascribed to this cause. It would appear from some portions of the series of August 26, that the long-continued exposure to the sun, in a nearly calm air, has produced an appreciable effect upon the readings of the thermometer, whether aspirated or free. Fortunately, with the exception of the ascent of August 26, the sun's radiation was never powerful; whilst on August 17, when the free thermometers were alone observed, the sun was scarcely ever visible. When the radiation was feeble, and the vertical motion of the balloon considerable, the two thermometers agreed very closely*. As hygrometers there is probably less difference in their value. In the examination of the results of the temperature observations, I have been led to prefer the indications of the aspirated thermometer. Regnault's Condensing Hygrometer†.—The only difference in the construction of this instrument, from that usually adopted by M. Regnault, was that the small tube, by which the air enters the reservoir to agitate the ether, had a funnel-shaped opening at top to facilitate the supply of ether. The bulb of the thermometer was cylindrical, $1\frac{1}{2}$ inch long, and $\frac{1}{10}$th of an inch diameter. The scale was of ivory, and the thermometer was fixed into the reservoir by a cork. No use was made of Daniell's hygrometer as that of M. Regnault was found much more convenient for such observations, being to a great extent self-acting. Polariscope.—This instrument was supplied by Mr. Darker of Lambeth. Its principle is the same as that employed in Mr. Wheatstone's "Polar Clock;" the parts of the polariscope used having, I believe, actually formed portions of one of those instruments. It exhibits the existence of polarization in a conspicuous manner. Exhausted Tubes for Collecting Air.—These tubes, which were constructed by Messrs. Negretti and Zambra, were about 9 inches long and $\frac{3}{4}$ inch diameter, fitted * It would be advisable in any future experiments to apply additional shades to all the thermometers, and if possible to use a larger general screen at some distance from them. † This instrument is described in the "Annuaire Météorologique de la France" for 1849, p. 221. with stopcocks. They were prepared by Dr. Miller previously to each ascent, and hermetically sealed immediately after their return to King's College. § 2. Observing Arrangements, Personal and Instrumental. It was deemed advisable that, in the first ascents at least, two observers should take part in the work. Mr. R. B. Nicklin, who for upwards of two years had been employed at the Kew Observatory and been practised in the observation of instruments, acted as my assistant in the first two ascents. Mr. Nicklin's aid was of essential service, and I wish to express my acknowledgement for the careful manner in which he took the observations with which he was entrusted, and for the readiness with which he assisted me on several occasions, sometimes at considerable personal inconvenience, when unforeseen difficulties arose. Having in these two ascents acquired experience in the observations, and having got the instruments into better working order, in the last two ascents I undertook the observations alone, thus obtaining the power of reaching a greater elevation. The car attached to the balloon was an oblong basket of wicker-work, about 6 feet long, 3 feet wide, and $2\frac{1}{2}$ feet deep. One end of this was occupied by the observers with the instruments, and the other by Mr. Green, who managed the balloon. A light board, a foot wide, was fixed across the car in front of the observers: at the extremity of this board, and projecting nearly a foot over the side of the car, was erected a light horizontal bar of wood, raised about 9 inches above the board, and inclined at an angle of about $45^\circ$ to its length, the board being cut away beyond the bar so as not to present any resistance to the circulation of the air. Upon the bar were fixed the thermometers and hygrometers. The aspirator was fixed to the lower side of the board, in which a hole was cut to admit the connecting tubes. On the first ascent the barometers were suspended from the hoop by which the car is attached to the netting of the balloon; this was however found to be inconvenient; and in the subsequent ascents they were suspended by gimbals from the cross board, their verticality being secured by weights attached to the lower ends of the cases. When seated in the car for observation, Mr. Nicklin occupying the right-hand corner and I the left, the stand supporting the thermometers was to my left, at a distance of about 18 inches; the aspirator being underneath the board, which served as a table before us: one barometer was immediately in front of Mr. Nicklin, and the other before myself; the observations could thus be readily taken without rising from our places. In order to obtain as continuous a record as possible of the variations of temperature and humidity, the observations were taken at very short intervals, generally at every minute, but frequently twice in a minute. In the first two ascents Mr. Nicklin observed one barometer, whilst I observed the thermometers and hygrometers, taking an occasional observation of the second barometer as a check upon the indications of the other. A watch which had been set to Greenwich time was placed in sight of both observers. In the last two ascents, when I was the only observer, the barometer was always read first, and immediately afterwards the thermometers and hygrometers; the whole time occupied being only a few seconds, the error, arising from the observations not being strictly simultaneous, must be very small. Notebooks were provided with columns ruled and headed for the different instruments. § 3. Circumstances of the Ascents and General Observations. The ascents were made with Mr. C. Green's large balloon, well known by the name of the "Royal Nassau." It has been fortunate, for the success of these experiments, that the Kew Committee obtained the cooperation of Mr. Green, whose pre-eminence as a skilful aéronaut has been established by upwards of 500 ascents; and whose control over his balloon is so complete, that no one who accompanies him can be otherwise than relieved from apprehension, and free to devote his attention calmly to the work before him. Mr. Green on all occasions showed the most anxious desire to contribute to the success of experiments, in which he took great interest. The ascents took place from the Royal Vauxhall Gardens, which were liberally placed at the disposal of the Committee by Mr. Wardell, the Lessee. The balloon was inflated with carburetted hydrogen gas, obtained from the Vauxhall and Phoenix Gas-works. First Ascent, August 17.—The weather, previously to the 17th, had been somewhat variable; on the 16th the wind changed from S.E. to S.W., and on the day of ascent it was from south. Clouds covered about three-fourths of the sky, the lowest stratum being a few detached masses of loose cumulus; a dense mass of cirrostratus (or stratus) being above, with perhaps occasional patches of cumulus intermediate. The ascent commenced at 3\textsuperscript{rd} 49\textsuperscript{m} P.M., after considerable difficulty had been experienced in the preliminary arrangements, owing to the force of the wind. A short time was lost at first in the attempt to put the instruments into more convenient order, and also from the novelty of the situation. The lowest clouds, which extended only over a small area, and were not near the balloon, were passed before they were noticed; their height was estimated at about 2500 feet. Between this height and about 13,000 feet, the air seemed free of clouds; after this, although the balloon was never in actual cloud, there seemed to be occasional masses of loose cumulus at no great distance. When at the greatest elevation, there was, at apparently a short distance above us, a thick mass of cloud, which was probably the cirrostratus which had been seen from the earth. About this time, and while still rising, a few small star-shaped crystals of snow about $\frac{1}{25}$th of an inch diameter fell upon us. The sun was almost constantly obscured throughout the ascent. The descent commenced at 4\textsuperscript{th} 46\textsuperscript{m} P.M., and the earth was reached about 5\textsuperscript{th} 20\textsuperscript{m} P.M., near Swavesey in Cambridgeshire, about 57 miles north of London. There seems to have been little, if any variation in the direction of the balloon's flight: it would thus appear that, within the height reached by us, the air was moving from south, at an average rate of about 38 miles an hour. A violent thunder-storm, with heavy rain, occurred about two hours after the descent took place, some symptoms of which were at one time noticed from the balloon at a great distance. In this ascent it was found impossible to use the aspirator, which was too large when two persons were seated. The free dry and wet thermometers were regularly observed. Some specimens of air were collected during the descent, and supplied to Dr. Miller. Second Ascent, August 26.—The wind on the 25th blew strongly from the west, but lulled in the evening. On the 26th it blew from east with moderate force; the sky was to a small extent obscured by detached masses of cumulus, and the sun shone brightly. The ascent took place at $4^h\ 43^m$ p.m., and observations were commenced at $4^h\ 46^m$. The clouds were again passed without being perceived, their height, however, was estimated at 3000 feet: above this height no clouds were met with, the sky being exceedingly clear and of a very deep blue colour. The currents of air passed through seem to have been from various directions, but generally moving with little rapidity. On leaving Vauxhall the balloon was at first carried towards the west for about 2 miles: when it reached the height of 5000 or 6000 feet it began to move slowly towards N.N.E. for about 4 miles, until about $5^h\ 25^m$, at an elevation of 12,000 feet, the direction of its motion, which was still for some time very slow, became W.N.W.; this direction it seems to have maintained during the remainder of the ascent, and probably with increased rapidity. The descent commenced at $7^h\ 0^m$, and the balloon reached the earth at $7^h\ 35^m$ p.m. near Chesham in the county of Bucks, about 25 miles W.N.W. of London. On this occasion all the instruments were regularly observed: some difficulty was experienced in the observation of Regnault's hygrometer, as the force of the aspirator was not sufficient to produce the great degree of cold required for the deposition of dew. This was remedied by Mr. Nicklin, who, at the cost of some exertion, maintained an increased strain upon the aspirator during the observations. The sun shone brightly throughout the ascent. Specimens of air were again collected during the descent. Third Ascent, October 21.—The weather had for a fortnight previously been fine, with an easterly wind; on the 19th the barometer began to fall and the east wind ceased; on the 20th the weather was fine, the air at the surface being calm, and the high clouds moving from S.W.: a fog existed on the night of the 20th, which slowly disappeared on the morning of the 21st, leaving the air in a very calm state and with some haze. A dense mass of cloud covered the sky, one or two slight showers falling about 10 a.m. I was the only observer on this occasion. The ascent commenced at $2^h\ 45^m$ p.m., and the balloon rose at first nearly vertically, but soon began to move towards E.N.E. Between the heights of 1000 and 2800 feet various detached and irregular masses of loose scud were encountered, but the balloon had not completely entered the dense mass of cloud till the height of nearly 3000 feet. At a height of 3700 feet the upper surface of the cloud was reached, and the sun was seen shining through thin cirrous clouds, at a great height. The height of the upper surface of the cloud was again observed during the descent at 4\textsuperscript{h} 6\textsuperscript{m} to be 3450 feet. When the balloon was close to the clouds, it was remarked that the general level of the surface was very uniform, presenting, however, a hillocky appearance; the irregularities being small, apparently not exceeding a very few feet. Shortly after clearing the clouds, a shadow of the balloon was seen on the surface fringed with a glory; with this shadow as a centre, there was also observed a circle of whitish light, the outer edge of it slightly tinged with yellow; its diameter being estimated at 80°. About this time there was noticed, stretching for a considerable length in a serpentine course over the surface of the cloud, a well-defined belt having the appearance of a broad road, both sides being strikingly distinct. When the balloon had attained a height of above 12,000 feet, Mr. Green, who had been watching its motion with reference to the clouds below, decided that, as it seemed to be moving rapidly from N.W., it would be prudent to descend below the clouds, to ascertain our position with reference to the sea, and if there should be space enough to ascend a second time to a greater height. It was found, however, on descending, that we were already very near the sea, indeed, moving along the river Thames within a short distance of its mouth. A second ascent being thus unadvisable, the descent was made at 4\textsuperscript{h} 20\textsuperscript{m} p.m. on the North bank of the Thames, between the villages of South Benfleet and Rayleigh in Essex, about 30 miles east of London. The average rate of motion was thus about 18 miles an hour, but in the higher part of our course it must have been considerably more. When about 3000 to 4000 feet above the clouds they were examined with the polariscope. The reflected light from the clouds next the sun showed no trace whatever of polarization: the slightly bluish-grey clouds on the side from the sun showed very slight symptoms of polarization, the light of the sky being strongly polarized. Fourth Ascent, November 10.—This ascent had been delayed for some days, owing to the unfavourable state of the weather, the wind having been generally from a westerly quarter. On the 10th the surface wind and the lower current of scud were moving very slowly from about N.E.: the upper clouds were only occasionally visible, and seemed to proceed from about N.N.W. The ascent commenced at 2\textsuperscript{h} 21\textsuperscript{m} 40\textsuperscript{s} p.m. At a height of 500 feet the first cloud, thin scud, was entered, the upper surface being 1970 feet high. A space of 2000 feet was clear of clouds, and at 4000 feet the second stratum of clouds was reached, its upper surface being found to be 4900 feet high. After this no clouds were met with, the sun shining through thin cirrous clouds, which must have been at a very great height. From notes taken at Vauxhall by Mr. Gassiot, it appears that, at starting, the balloon moved towards south-west until 2\textsuperscript{h} 26\textsuperscript{m}, when, just as it had reached the upper surface of the first stratum of clouds, or at a height of about 2000 feet, the direction became easterly. Bearings MDCCCLIII. and altitudes taken by Mr. Glaisyer show that at $2^h 44^m$, when the height was 11,000 feet, the balloon was 5 miles S. by E. of Greenwich Observatory. The greatest elevation (22,930 feet) was reached at $3^h 16^m$ p.m.; about which time the clouds, which had hitherto obscured the earth, had disappeared, and we perceived that the balloon was rapidly approaching the sea. Mr. Green discharged gas copiously, and the descent became very rapid; a landing being effected within 4 miles of the sea, accompanied by a considerable shock which broke several of the instruments. The descent took place, between $3^h 40^m$ and $3^h 45^m$, at Acryse near Folkestone, about 57 miles E.S.E. from London. The time occupied in moving from a little S.W. of Vauxhall to 5 miles S. by E. of Greenwich, or about 9 miles, was 18 minutes; the remainder of the distance to Acryse, about 50 miles, being accomplished in from 55 to 60 minutes, or at the rate of fully 50 miles an hour. As the height reached on this occasion was considerably greater than in the previous ascents, the effect of the diminished pressure was more severely felt; both Mr. Green and myself having experienced considerable difficulty in respiration, with much breathlessness and fatigue after any muscular exertion. § 4. Description of the Table of Observations. All the meteorological observations taken during the ascents are contained in Table I. Column 1 contains the times at which the observations were made. Column 2 contains the readings of the thermometer attached to the barometer. Column 3 contains the observations of the barometer corrected for temperature, by Schumacher's tables, and for scale error. The numbers, to which the mark $\dagger$ is affixed, in the observations of August 17 and 26, are the occasional readings by myself of the second barometer. The readings of the barometer were made by estimation to 0·01 inch; but the probable error of an observation, from various causes,—such as rapid change in the height, and the occasional oscillation of the mercury from agitation of the car,—is perhaps 0·03 inch, or even sometimes more. This degree of accuracy appears, however, to be quite sufficient with reference to the changes of the temperature and humidity; an error of 30 or 40 feet in the resulting height being equivalent in general to a change of only one-tenth of a degree of temperature. Column 4 contains the height above the level of the sea, as deduced from the barometric readings by the formula of Laplace. The formula actually employed was $$z = \log \left( \frac{h}{l} \right) \times 18336 \left( 1 + \frac{2(t+t')}{1000} \right) \left( 1 + 0·002837 \cos 2L \right) \left( 1 + \frac{z+15926}{6366200} \right);$$ or expressed in English feet and Fahrenheit's degrees, $$z = \log \left( \frac{h}{l} \right) \times 60159 \left( 1 + \frac{t+t'-64}{900} \right) \left( 1 + 0·002837 \cos 2L \right) \left( 1 + \frac{z+52251}{20886900} \right),$$ where $z$ is the height required; $h$ and $h'$, $t$ and $t'$ the height of the barometer cor- * Annuaire Météorologique de la France, 1849, page 54. rected for temperature, and the temperature of the air, at the lower and upper stations respectively; L, the latitude. The temperature of the air for the position of the balloon has been derived from the readings of the aspirated dry thermometer (column 5), except on August 17, when the free thermometer only was observed. The temperature and barometric height at the earth's surface have been taken by interpolation from the comparative observations at different stations; the mean height above the sea, of the stations referred to, having been included. The numbers, it will be seen, have been given only to the nearest 10 feet. Many observers in different parts of the country made corresponding meteorological observations, generally at hourly intervals, on the days of the several ascents. These have been arranged in compact tabular order by Colonel Sykes, Chairman of the Kew Committee, and are appended to this report. The stations selected for comparison with the different days' observations have been those which lay nearest to the course of the balloon. The temperature of the air at the surface of the earth, has been derived from the mean of the observations at all the selected stations, both as regards its absolute value and hourly change. The hourly change of the barometer has been taken from the observations at all the selected stations; but its absolute height has always been derived from the mean of the observations at the Royal Observatory, Greenwich, and at the residence of James Glaisher, Esq., Lewisham. The error likely to result from adopting the height at these two stations as the standard of reference will be in any case very small, and can only affect the absolute and not the relative heights of the balloon by a few feet; while any uncertainty with regard to the index errors of other barometers is obviated. The quantity +0·028 has been added to the readings of the terrestrial barometers, on account of the index errors of the balloon barometers. The following are the stations whose observations have been employed, and the resulting mean values for each day of ascent. August 17, 5 stations, viz.—Greenwich; Lewisham; Enfield; St. John's Wood; Cambridge. Mean temperature of the air at 4\textsuperscript{th} P.M. = 71°2; hourly change = −1°1. Mean height of the barometer at 4\textsuperscript{th} P.M. = 29·740 in.; hourly change = −0·036 in. August 26, 5 stations, viz.—Greenwich; Lewisham; St. John's Wood; Kew Observatory; Stone Rectory, Bucks. | Time | Temperature of the Air | Barometer | |------|-----------------------|-----------| | | Mean. | Hourly Change. | Mean Height. | Hourly Change. | | h | ° | ° | in. | in. | | 4 P.M. | 69·7 | −2·2 | 29·949 | +0·010 | | 5 | 67·5 | −2·3 | ·959 | +0·005 | | 6 | 65·2 | −2·5 | ·964 | +0·021 | | 7 | 62·7 | | ·985 | | 2 u 2 October 21, 2 stations, viz.—Greenwich and Lewisham. | Temperature of the Air | Barometer | |------------------------|-----------| | Time. | Mean. | Half-hourly Change. | Mean Height. | Half-hourly Change. | | h m | ° | ° | in. | in. | | 2 30 P.M. | 58·7 | 0·0 | 29·900 | -0·001 | | 3 0 | 58·7 | -1·0 | ·899 | -·004 | | 3 30 | 57·7 | -0·8 | ·895 | -·007 | | 4 0 | 56·9 | -0·8 | ·888 | ·000 | | 4 30 | 56·1 | | ·888 | | November 10, 2 stations,—Greenwich and Lewisham. | Temperature of the Air | Barometer | |------------------------|-----------| | Time. | Greenwich. | Lewisham. | Mean. | Mean Height. | Half-hourly Change. | | h m | ° | ° | ° | in. | in. | | 2 30 P.M. | 48·6 | 50·7 | 49·7 | 29·978 | -0·003 | | 3 0 | 48·0 | 49·3 | 48·7 | ·975 | -·004 | | 3 30 | 49·0 | 49·6 | 49·3 | ·971 | | | Mean . . . . . | 49·2 | | | | | As the progress of the temperature at these two stations has been very irregular and indefinite, a mean result has been adopted, and no allowance made for hourly change. The height, above the mean sea level, of Greenwich = 159 feet. The height, above the mean sea level, of Lewisham = 80 feet. Mean of both stations . . . . . = 120 feet. Columns 5–10 contain the results of observations with the aspirated dry and wet thermometers; the tension of vapour, relative humidity (100 being complete saturation), and the calculated temperature of the dew-point having been deduced by Dr. Arjohn's formula and Dalton's Tables of the elasticity of vapour. Column 11 contains the readings of the dry thermometer, corrected for hourly change by means of the numbers deduced above from observations at different stations. The numbers in this column have been employed in the subsequent discussions and in the projected results. Columns 12–17 contain the observations of the free dry and wet thermometers similarly reduced. Columns 18 and 19 contain the results of the direct dew-point observations with Regnault's Hygrometer, and the corresponding tension of vapour derived from Dalton's Table. When numbers are entered in column 18 with the sign — after them, it is meant that the temperature in the hygrometer had been lowered to the degree stated, but that no dew was deposited. All the readings of both pairs of dry and wet thermometers have been corrected for index error; the corrections to the dew-point thermometer were very small, and have been neglected. ### Table I.—Meteorological Observations made in the Four Balloon Ascents of August 17, August 26, October 21, and November 10, 1852. | Greenwich Mean Time | Barometer | Height above sea level | Dry and Wet Thermometers, aspirated | Temperature corrected for charge | Dry and Wet Thermometers, free | Regnault's Hygrometer | |---------------------|-----------|------------------------|------------------------------------|---------------------------------|-------------------------------|----------------------| | | Therm. | Reading corrected. | Dry. | Wet. | Diff. | Tension of vapor. | Relative humidity. | Dew-point. | Temperature corrected for charge | Dry. | Wet. | Diff. | Tension of vapor. | Relative humidity. | Dew-point. | Dew-point. | | | | | | | | | | | | | | | | | | | | h m s | in. | feet | ° | ° | ° | in. | ° | ° | | | | | | | | | | 3 52 0 | 27°40 | 2,440 | 62°8 | 63°0 | 60°4 | 2°6 | 50°3 | 87 | 58°8 | | | | | | | | | 54 0 | 26°40 | 3,470 | 59°2 | 59°4 | 57°1 | 2°3 | 45°1 | 88 | 55°6 | | | | | | | | | 54 0 70 | 26°42+ | 3,450 | 58°1 | 58°2 | 55°3 | 2°9 | 41°8 | 85 | 53°3 | | | | | | | | | 55 0 | 25°80 | 4,110 | 57°8 | 57°8 | 43°4 | 14°4 | 16°4 | 34 | 26°6 | | | | | | | | | 59 0 | 24°22 | 5,880 | | | | | | | | | | | | | | | | 59 18 | 66°5 | 6,020 | | | | | | | | | | | | | | | | 59 30 | 23°62 | 6,580 | | | | | | | | | | | | | | | | 4 0 30 | | | | | | | | | | | | | | | | | | 1 0 | 23°42 | 6,800 | | | | | | | | | | | | | | | | 1 30 | 23°33 | 6,910 | | | | | | | | | | | | | | | | 2 0 | 23°13 | 7,140 | | | | | | | | | | | | | | | | 2 0 63°0 | 22°96+ | 7,350 | | | | | | | | | | | | | | | | 2 30 | 22°93 | 7,380 | | | | | | | | | | | | | | | | 3 0 | 22°78 | 7,550 | | | | | | | | | | | | | | | | 3 30 | 22°83 | 7,480 | | | | | | | | | | | | | | | | 4 0 | 22°43 | 7,970 | | | | | | | | | | | | | | | | 4 30 | 22°33 | 8,100 | | | | | | | | | | | | | | | | 5 0 | 22°14 | 8,340 | | | | | | | | | | | | | | | | 5 0 61°0 | 22°13+ | 8,350 | | | | | | | | | | | | | | | | 5 30 | 22°04 | 8,460 | | | | | | | | | | | | | | | | 6 0 | 21°94 | 8,590 | | | | | | | | | | | | | | | | 6 30 | 21°84 | 8,710 | | | | | | | | | | | | | | | | 7 0 | 21°84 | 8,700 | | | | | | | | | | | | | | | | 7 30 | 21°84 | 8,690 | | | | | | | | | | | | | | | | 8 0 | 21°74 | 8,810 | | | | | | | | | | | | | | | | 9 30 | 21°49 | 9,130 | | | | | | | | | | | | | | | | 10 0 | 21°49 | 9,120 | | | | | | | | | | | | | | | | 10 30 | 21°34 | 9,310 | | | | | | | | | | | | | | | | 11 0 | 21°24 | 9,430 | | | | | | | | | | | | | | | | 11 30 | 21°13 | 9,560 | | | | | | | | | | | | | | | | 12 0 | 21°00 | 9,730 | | | | | | | | | | | | | | | | 12 30 | 20°78+ | 10,020 | | | | | | | | | | | | | | | | 13 0 | 20°65 | 10,180 | | | | | | | | | | | | | | | | 13 0 | 20°62+ | 10,220 | | | | | | | | | | | | | | | | 13 30 | 20°45 | 10,440 | | | | | | | | | | | | | | | | 14 0 | 20°25 | 10,700 | | | | | | | | | | | | | | | | 14 0 54°0 | 20°27+ | 10,680 | | | | | | | | | | | | | | | | 14 30 | 20°10 | 10,900 | | | | | | | | | | | | | | | | 15 0 | 20°06 | 10,950 | | | | | | | | | | | | | | | | 15 15 | 19°76+ | 11,360 | | | | | | | | | | | | | | | | 15 30 | 19°80 | 11,290 | | | | | | | | | | | | | | | | 16 0 | 19°52 | 11,680 | | | | | | | | | | | | | | | | 16 15 | 19°57+ | 11,600 | | | | | | | | | | | | | | | | 16 30 | 19°51 | 11,690 | | | | | | | | | | | | | | | | 17 0 | 19°40 | 11,840 | | | | | | | | | | | | | | | | 17 30 | 19°35 | 11,900 | | | | | | | | | | | | | | | | 18 0 | 19°25 | 12,040 | | | | | | | | | | | | | | | | 18 30 | 19°15 | 12,180 | | | | | | | | | | | | | | | | 19 0 | 19°14 | 12,200 | | | | | | | | | | | | | | | | 19 30 | 19°15 | 12,190 | | | | | | | | | | | | | | | | 20 0 | 19°16 | 12,150 | | | | | | | | | | | | | | | | 20 20 | 19°15+ | 12,160 | | | | | | | | | | | | | | | | 20 30 | 19°16 | 12,140 | | | | | | | | | | | | | | | | 21 0 | 19°15 | 12,160 | | | | | | | | | | | | | | | | 21 30 | 19°06 | 12,280 | | | | | | | | | | | | | | | | 22 0 | 18°91 | 12,500 | | | | | | | | | | | | | | | | 22 20 | 18°87+ | 12,550 | | | | | | | | | | | | | | | | 22 30 | 18°66 | 12,860 | | | | | | | | | | | | | | | | Greenwich Mean Time | Barometer | Height above sea-level | Dry and Wet Thermometers, aspirated | Temperature corrected for change | Dry and Wet Thermometers, free | Dew-point. | Tension of vapour. | |---------------------|-----------|------------------------|-----------------------------------|---------------------------------|-----------------------------|------------|-------------------| | | | | Dry. | Wet. | Diff. | Relative humidity. | Dew-point. | Dry. | Wet. | Diff. | Relative humidity. | Dew-point. | Tension of vapour. | | h m s | in. | feet. | ° | ° | ° | ° | ° | ° | ° | ° | ° | ° | ° | | 4 23 0 | 18·56 | 13,000 | 33·7 | 33·2 | 31·3 | 1·9 | 1·82 | 88 | 29·5 | 30·3 | 29·8 | 28·4 | 27·9 | 26·6 | 1·3 | 1·56 | 89 | 25·2 | | 24 0 | 18·21 | 13,470 | 28·4 | 27·9 | 26·6 | 1·3 | 1·56 | 89 | 25·2 | 27·5 | 27·0 | 25·9 | 25·9 | 25·0 | 1·5 | 1·46 | 89 | 23·4 | | 24 15 | 18·13+ | 13,590 | 27·0 | 26·5 | 25·0 | 1·5 | 1·46 | 89 | 23·4 | 27·1 | 26·6 | 24·6 | 2·0 | 1·41 | 86 | 22·4 | | 24 30 | 18·11 | 13,610 | 25·5 | 24·9 | 23·4 | 1·5 | 1·37 | 89 | 21·6 | 24·9 | 24·3 | 23·0 | 1·3 | 1·36 | 90 | 21·4 | | 25 0 | 17·87 | 13,960 | 24·9 | 24·3 | 23·0 | 1·3 | 1·36 | 90 | 21·4 | 25·3 | 24·7 | 23·0 | 1·7 | 1·34 | 87 | 21·0 | | 25 30 | 17·77 | 14,100 | 24·9 | 24·3 | 22·6 | 1·7 | 1·32 | 87 | 20·6 | 24·9 | 24·3 | 22·6 | 1·7 | 1·32 | 87 | 20·6 | | 25 30 | 17·82+ | 14,020 | 21·5 | 20·9 | 18·4 | 1·4 | 1·14 | 89 | 16·6 | 20·4 | 19·8 | 18·0 | 1·4 | 1·12 | 88 | 16·1 | | 26 0 | 17·47 | 14,550 | 20·5 | 19·8 | 18·3 | 1·5 | 1·13 | 88 | 16·4 | 20·5 | 19·8 | 17·7 | 2·1 | 1·07 | 84 | 14·9 | | 26 20 | 17·39+ | 14,680 | 21·7 | 21·0 | 16·1 | 4·9 | 0·85 | 63 | 8·7 | 20·0 | 19·7 | 17·7 | 2·0 | 1·08 | 84 | 15·1 | | 26 30 | 17·37 | 14,710 | 20·5 | 19·8 | 17·0 | 2·8 | 1·01 | 79 | 13·3 | 20·4 | 19·7 | 19·3 | 1·9 | 0·96 | 78 | 12·0 | | 27 0 | 17·27 | 14,850 | 18·8 | 18·1 | 14·1 | 4·0 | 0·83 | 69 | 8·1 | 18·6 | 17·9 | 14·4 | 3·5 | 0·87 | 73 | 9·3 | | 27 15 | 17·08+ | 15,150 | 12·1 | 11·3 | 7·2 | 4·1 | 0·60 | 64 | 0·5 | 11·2 | 10·4 | 6·7 | 3·7 | 0·61 | 67 | 0·1 | | 27 30 | 17·06 | 15,170 | 13·2 | 12·4 | 7·5 | 4·9 | 0·57 | 58 | -1·8 | 13·5 | 12·7 | 8·1 | 4·6 | 0·60 | 61 | -0·5 | | 27 45 | 16·97+ | 15,310 | 13·6 | 12·8 | 7·3 | 5·5 | 0·53 | 53 | -3·7 | 14·0 | 13·3 | 7·2 | 6·1 | 0·49 | 49 | -5·8 | | 28 0 | 16·97 | 15,310 | 13·5 | 12·7 | 8·1 | 4·6 | 0·60 | 61 | -0·5 | 9·8 | 9·0 | 6·4 | 2·6 | 0·65 | 76 | +1·6 | | 28 20 | 16·98+ | 15,290 | 10·5 | 9·7 | 7·7 | 2·0 | 0·72 | 82 | 4·3 | 9·5 | 8·7 | 6·6 | 2·1 | 0·68 | 80 | 2·8 | | 28 30 | 16·96 | 15,330 | 8·7 | 7·9 | 6·3 | 1·6 | 0·70 | 85 | 3·6 | 8·7 | 7·9 | 6·3 | 1·6 | 0·70 | 85 | 3·6 | August 17, 1852. REGNAULT's Hygrometer. Dew-point. | Tension of vapour. -----------|------------------- ° | ° in. | in. ## OBSERVATIONS IN FOUR BALLOON ASCENTS. ### Table I. (Continued.) | Greenwich Mean Time | Barometer | Height above sea-level | Dry and Wet Thermometers, aspirated | Temperature corrected for change | Dry and Wet Thermometers, free | Regnault's Hygrometer | |---------------------|-----------|------------------------|------------------------------------|---------------------------------|-------------------------------|----------------------| | | | | Dry. | Wet. | Diff. | Tension of vapour. | Relative humidity. | Dew-point. | Dry. | Wet. | Diff. | Tension of vapour. | Relative humidity. | Dew-point. | Tension of vapour. | | | | | | | | in. | | Dew-point. | | | | in. | | Dew-point. | in. | | | | | | | | | | | | | | | | | | | August 17, 1852. | | | | | | | | | | | | | | | | | h m s | in. | feet. | | | | | | | | | | | | | | | 4 47 0 | 14·46 | 19,300 | | | | | | | | | | | | | | | 47 30 | 14·86 | 18,630 | | | | | | | | | | | | | | | 49 0 | 15·17 | 18,090 | | | | | | | | | | | | | | | 50 0 | 15·27 | 17,920 | | | | | | | | | | | | | | | 50 30 | 15·48 | 17,580 | | | | | | | | | | | | | | | 51 0 | 15·58 | 17,420 | | | | | | | | | | | | | | | 51 30 | 15·63 | 17,330 | | | | | | | | | | | | | | | 52 0 | 15·88 | 16,920 | | | | | | | | | | | | | | | 52 15 | 15·93 | 17,010 | | | | | | | | | | | | | | | 52 30 | 16·08 | 16,590 | | | | | | | | | | | | | | | 53 0 | 16·39 | 16,090 | | | | | | | | | | | | | | | 54 0 | 16·59 | 15,790 | | | | | | | | | | | | | | | 54 30 | 16·89 | 15,320 | | | | | | | | | | | | | | | 55 0 | 17·10 | 15,000 | | | | | | | | | | | | | | | 56 45 | 17·77 | 14,020 | | | | | | | | | | | | | | | 57 0 | 18·11 | 13,530 | | | | | | | | | | | | | | | 57 40 | 18·36 | 13,170 | | | | | | | | | | | | | | | 58 0 | 18·71 | 12,680 | | | | | | | | | | | | | | | 5 0 30 | 19·57 | 11,500 | | | | | | | | | | | | | | | 1 30 | 20·28 | 10,570 | | | | | | | | | | | | | | | 3 0 | 20·88 | 9,790 | | | | | | | | | | | | | | | 5 0 | 22·31 | 8,020 | | | | | | | | | | | | | | | 5 30 | 22·51 | 7,780 | | | | | | | | | | | | | | | 6 0 | 22·91 | 7,310 | | | | | | | | | | | | | | | August 26, 1852. | | | | | | | | | | | | | | | | | h m s | in. | feet. | | | | | | | | | | | | | | | 4 46 0 | 29·34 | 710 | | | | | | | | | | | | | | | 47 0 | 29·18 | 860 | | | | | | | | | | | | | | | 47 30 | 29·19 | 850 | | | | | | | | | | | | | | | 48 0 | 28·89 | 1,140 | | | | | | | | | | | | | | | 49 0 | 28·40 | 1,620 | | | | | | | | | | | | | | | 50 0 | 28·10 | 1,920 | | | | | | | | | | | | | | | 51 0 | 27·85 | 2,160 | | | | | | | | | | | | | | | 52 0 | 27·70 | 2,310 | | | | | | | | | | | | | | | 53 0 | 27·40 | 2,620 | | | | | | | | | | | | | | | 54 0 | 27·11 | 2,910 | | | | | | | | | | | | | | | 55 0 | 26·90 | 3,120 | | | | | | | | | | | | | | | 56 0 | 26·41 | 3,630 | | | | | | | | | | | | | | | 57 0 | 26·16 | 3,900 | | | | | | | | | | | | | | | 58 0 | 25·77 | 3,890 | | | | | | | | | | | | | | | 59 0 | 25·44 | 4,300 | | | | | | | | | | | | | | | 59 30 | 25·10 | 4,780 | | | | | | | | | | | | | | | 5 0 | 24·92 | 5,230 | | | | | | | | | | | | | | | 1 0 | 24·47 | 5,710 | | | | | | | | | | | | | | | 2 0 | 24·12 | 6,100 | | | | | | | | | | | | | | | 3 0 | 23·68 | 6,590 | | | | | | | | | | | | | | | 4 0 | 23·36 | 7,080 | | | | | | | | | | | | | | | 4 40 | 23·04 | 7,570 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Greenwich Mean Time | Barometer | Height above sea-level | Dry and Wet Thermometers, aspirated | Dry and Wet Thermometers, free | Regnault's Hygrometer | |---------------------|-----------|------------------------|-----------------------------------|-------------------------------|----------------------| | | | | Dry. Wet. Diff. Tension of vapour. Relative humidity. Dew-point. Temperature corrected for change. | Dry. Wet. Diff. Tension of vapour. Relative humidity. Dew-point. | Dew-point. Tension of vapour. | | h m s | in. | feet. | | | | | 5 5 0 | 23-13 | 7,230 | 41-0 39-8 1-2 252 92 38-7 41-7 43-6 40-9 2-7 249 83 38-3 | | 6 0 | 22-78 | 7,650 | 40-8 35-7 5-1 183 67 29-6 41-5 | | 6 30 | 22-33 | 8,200 | 42-3 31-0 11-3 107 37 14-9 43-1 | | 7 0 | 22-08 | 8,510 | 42-4 30-0 12-4 092 32 10-8 43-2 | | 8 0 | 21-74 | 8,940 | 41-7 29-0 12-7 073 26 4-7 42-5 42-7 32-0 10-7 110 38 15-7 | | 9 0 | 21-54 | 9,190 | 41-3 29-0 12-3 082 30 7-8 42-0 42-2 31-7 10-0 123 44 18-7 | | 10 0 | 21-44 | 9,320 | 41-7 30-0 11-7 099 35 12-8 42-6 | | 11 0 | 21-32 | 9,480 | 42-5 32-0 10-5 113 39 16-4 43-4 43-6 34-9 8-7 150 50 24-1 | | 12 0 | 21-24 | 9,580 | 41-8 29-5 12-3 092 33 10-8 42-8 44-0 32-0 12-0 102 34 13-6 | | 13 0 | 21-14 | 9,690 | 42-3 29-5 12-8 088 31 9-6 43-3 | | 14 0 | 21-04 | 9,820 | 40-9 27-2 13-7 068 25 2-8 41-9 | | 15 0 | 20-94 | 9,970 | 39-8 26-6 13-2 069 26 3-2 40-8 42-7 30-1 12-6 095 33 11-7 | | 16 0 | 20-85 | 10,100 | 42-0 30-6 11-4 107 38 14-9 43-1 44-5 33-4 11-1 120 39 18-0 | | 17 0 | 20-75 | 10,200 | 39-8 28-5 11-3 095 36 11-7 40-9 42-3 31-6 10-7 120 42 18-0 | | 18 0 | 20-74 | 10,210 | 40-0 29-7 10-3 108 41 15-1 41-2 42-3 32-0 10-3 118 41 17-5 | | 19 0 | 20-70 | 10,260 | 41-8 31-0 10-8 113 40 16-4 43-0 | | 20 0 | 20-65 | 10,290 | 42-7 32-0 10-7 114 39 16-6 43-9 43-4 34-6 8-8 149 50 23-9 | | 21 0 | 20-59 | 10,340 | 43-8 32-6 11-2 114 38 16-6 45-1 | | 22 0 | 20-54 | 10,420 | 40-8 29-4 11-4 101 37 13-4 42-1 | | 23 0 | 20-43 | 10,620 | 40-2 28-4 11-8 092 35 10-8 41-6 42-8 32-4 10-4 121 41 18-2 | | 24 0 | 20-25 | 10,840 | 39-5 28-1 11-4 094 36 11-4 40-9 | | 25 0 | 20-10 | 11,050 | 38-5 28-1 10-4 102 41 13-6 40-0 39-4 30-5 8-9 127 49 19-5 | | 26 0 | 20-15 | 10,980 | 38-4 28-1 10-3 102 41 13-6 39-9 39-0 30-2 8-8 126 49 19-3 | | 27 0 | 20-20 | 10,920 | 38-9 29-1 9-7 113 45 16-4 40-3 | | 28 0 | 20-28 | 10,810 | 39-1 28-5 10-6 102 40 13-6 40-6 39-4 30-9 8-5 133 52 20-8 | | 29 0 | 20-14 | 10,970 | 35-4 25-9 9-5 094 42 11-4 37-0 | | 30 0 | 19-95 | 11,210 | 34-0 25-1 8-9 094 44 11-4 35-6 36-2 27-1 9-1 104 45 14-1 | | 31 0 | 19-80 | 11,440 | 36-0 26-9 9-1 104 45 14-1 37-7 | | 32 0 | 19-73 | 11,540 | 35-9 27-0 8-9 106 46 14-6 37-6 35-6 28-1 7-5 122 54 18-4 | | 33 0 | 19-65 | 11,650 | 36-8 26-6 9-6 103 44 13-9 38-5 | | 34 0 | 19-59 | 11,740 | 37-2 26-8 10-4 095 40 11-7 39-0 | | 35 0 | 19-59 | 11,740 | 37-3 27-2 10-1 100 42 13-1 39-1 40-0 31-6 8-4 140 53 22-2 | | 36 0 | 19-60 | 11,730 | 38-8 28-1 10-7 101 40 13-3 39-8 | | 37 0 | 19-64 | 11,650 | 36-8 27-2 9-6 103 44 13-9 38-7 | | 38 0 | 19-60 | 11,690 | 35-7 25-8 9-9 093 41 11-1 37-6 | August 26, 1852. ## OBSERVATIONS IN FOUR BALLOON ASCENTS. ### TABLE I. (Continued.) | Greenwich Mean Time | Barometer | Height above sea-level | Dry and Wet Thermometers, aspirated | Temperature corrected for change | Dry and Wet Thermometers, free | Regnault's Hygrometer | |---------------------|-----------|------------------------|------------------------------------|---------------------------------|-------------------------------|----------------------| | | | | Dry. | Wet. | Diff. | Tension of vapour | Relative humidity | Dew-point | Temperature corrected for change | Dry. | Wet. | Diff. | Tension of vapour | Relative humidity | Dew-point | Dew-point | Tension of vapour | | h m s | in. | feet | | | | | | | | | | | | | | | | | 5 38 30 | 19·55 | 11,730 | 33·6 | 23·8 | 9·8 | 0·082 | 39 | 7·7 | 35·6 | | | | | | | | | | 39 0 | 11,730 | 32·5 | 22·8 | 9·7 | 0·77 | 38 | 6·1 | 34·5 | | | | | | | | | | | 39 30 | 11,790 | 32·9 | 23·8 | 10·1 | 0·75 | 36 | 5·4 | 34·9 | | | | | | | | | | | 40 0 | 11,840 | 34·0 | 23·3 | 10·7 | 0·74 | 35 | 5·0 | 36·0 | | | | | | | | | | | 40 30 | 11,830 | 34·7 | 23·6 | 11·1 | 0·73 | 33 | 4·7 | 36·8 | | | | | | | | | | | 41 0 | 11,830 | 34·7 | 23·6 | 11·1 | 0·73 | 33 | 4·7 | 36·8 | | | | | | | | | | | 41 30 | 12,050 | 33·9 | 23·2 | 10·7 | 0·74 | 35 | 5·0 | 36·0 | | | | | | | | | | | 42 0 | 12,150 | 34·9 | 24·7 | 10·2 | 0·85 | 38 | 8·7 | 37·0 | | | | | | | | | | | 42 30 | 12,220 | 32·7 | 22·3 | 10·4 | 0·72 | 35 | 4·3 | 34·8 | | | | | | | | | | | 43 0 | 12,280 | 31·9 | 21·9 | 10·0 | 0·73 | 37 | 4·7 | 34·1 | | | | | | | | | | | 44 0 | 12,330 | 31·9 | 22·1 | 9·8 | 0·73 | 38 | 5·4 | 34·1 | | | | | | | | | | | 44 30 | 12,360 | 29·0 | 21·3 | 7·7 | 0·85 | 47 | 8·7 | 31·3 | | | | | | | | | | | 45 0 | 12,390 | 29·2 | 21·1 | 8·1 | 0·81 | 45 | 7·4 | 31·5 | | | | | | | | | | | 46 0 | 12,420 | 29·0 | 21·1 | 7·9 | 0·83 | 46 | 8·1 | 31·3 | | | | | | | | | | | 47 0 | 12,470 | 30·9 | 23·2 | 7·7 | 0·91 | 47 | 10·5 | 33·2 | | | | | | | | | | | 48 0 | 12,480 | 31·5 | 23·4 | 8·1 | 0·93 | 47 | 11·1 | 33·8 | | | | | | | | | | | 49 0 | 12,540 | 32·5 | 24·2 | 8·3 | 0·96 | 47 | 12·0 | 34·8 | | | | | | | | | | | 50 0 | 12,580 | 34·7 | 26·2 | 8·5 | 1·06 | 48 | 14·6 | 37·1 | | | | | | | | | | | 50 30 | 12,610 | 34·1 | 26·1 | 8·0 | 1·09 | 51 | 15·4 | 36·5 | | | | | | | | | | | 51 0 | 12,610 | 30·9 | 24·7 | 6·2 | 1·13 | 59 | 16·4 | 33·3 | | | | | | | | | | | 51 30 | 12,690 | 29·9 | 21·9 | 7·7 | 0·88 | 48 | 9·6 | 32·1 | | | | | | | | | | | 52 0 | 12,740 | 29·6 | 21·9 | 7·7 | 0·88 | 48 | 9·6 | 32·1 | | | | | | | | | | | 52 30 | 12,840 | 28·9 | 21·3 | 7·6 | 0·86 | 48 | 9·0 | 31·4 | | | | | | | | | | | 53 0 | 12,890 | 27·6 | 20·5 | 7·1 | 0·86 | 50 | 9·0 | 30·1 | | | | | | | | | | | 53 30 | 12,930 | 27·0 | 20·3 | 6·7 | 0·87 | 52 | 9·3 | 29·5 | | | | | | | | | | | 54 0 | 12,960 | 27·2 | 20·4 | 6·8 | 0·87 | 52 | 9·3 | 29·7 | | | | | | | | | | | 55 0 | 12,990 | 28·7 | 21·8 | 6·9 | 0·93 | 52 | 11·1 | 31·3 | | | | | | | | | | | 56 0 | 13,020 | 30·0 | 23·2 | 6·8 | 1·01 | 54 | 13·3 | 32·6 | | | | | | | | | | | 56 30 | 13,060 | 35·4 | 27·1 | 8·3 | 1·14 | 51 | 16·6 | 38·1 | | | | | | | | | | | 57 0 | 13,100 | 35·1 | 27·1 | 8·0 | 1·15 | 52 | 16·8 | 37·8 | | | | | | | | | | | 57 30 | 13,140 | 34·2 | 25·9 | 8·3 | 1·06 | 49 | 14·6 | 36·9 | | | | | | | | | | | 58 0 | 13,180 | 34·9 | 26·4 | 8·5 | 1·07 | 49 | 14·9 | 37·6 | | | | | | | | | | | 58 30 | 13,220 | 35·8 | 27·3 | 8·5 | 1·13 | 50 | 16·4 | 38·6 | | | | | | | | | | | 59 0 | 13,260 | 36·4 | 26·0 | 10·4 | 0·91 | 39 | 10·5 | 39·2 | | | | | | | | | | | 6 0 | 13,300 | 35·0 | 24·7 | 10·3 | 0·84 | 38 | 8·4 | 37·8 | | | | | | | | | | | 1 0 | 13,340 | 34·6 | 24·9 | 9·7 | 0·89 | 41 | 9·9 | 37·5 | | | | | | | | | | | 2 0 | 13,380 | 32·5 | 24·2 | 8·3 | 0·95 | 47 | 11·7 | 35·4 | | | | | | | | | | | 3 0 | 13,420 | 33·1 | 25·2 | 7·9 | 1·03 | 50 | 13·9 | 36·0 | | | | | | | | | | | 4 0 | 13,460 | 32·7 | 25·2 | 7·5 | 1·06 | 50 | 14·6 | 35·7 | | | | | | | | | | | 5 0 | 13,500 | 29·5 | 23·2 | 6·3 | 1·03 | 57 | 13·9 | 32·5 | | | | | | | | | | | 6 0 | 13,540 | 29·0 | 22·8 | 6·2 | 1·02 | 57 | 13·6 | 32·0 | | | | | | | | | | | 7 30 | 13,580 | 33·5 | 26·8 | 6·7 | 1·22 | 58 | 18·5 | 36·6 | | | | | | | | | | | 9 0 | 13,620 | 33·9 | 27·0 | 6·9 | 1·21 | 57 | 18·2 | 37·0 | | | | | | | | | | | 11 0 | 13,660 | 32·1 | 23·7 | 8·4 | 0·91 | 45 | 10·5 | 35·4 | | | | | | | | | | | 12 0 | 13,700 | 33·6 | 25·0 | 8·6 | 0·98 | 46 | 12·5 | 37·0 | | | | | | | | | | | 13 0 | 13,740 | 32·4 | 24·4 | 8·0 | 0·99 | 49 | 12·8 | 35·8 | | | | | | | | | | | 14 0 | 13,780 | 32·9 | 25·2 | 7·7 | 1·05 | 51 | 14·4 | 36·3 | | | | | | | | | | | 15 0 | 13,820 | 31·2 | 24·2 | 7·0 | 1·05 | 54 | 14·4 | 34·7 | | | | | | | | | | | 16 0 | 13,860 | 31·2 | 24·2 | 7·0 | 1·05 | 54 | 14·4 | 34·7 | | | | | | | | | | August 26, 1862. MDCCCLIII. ## Table I. (Continued.) | Greenwich Mean Time | Barometer | Height above sea-level | Dry and Wet Thermometers, aspirated | Dry and Wet Thermometers, free | |---------------------|-----------|------------------------|------------------------------------|--------------------------------| | | | | Dry. | Wet. | Diff. | Tension of vapour. | Relative humidity. | Dew-point. | Temperature corrected for change. | Dry. | Wet. | Diff. | Tension of vapour. | Relative humidity. | Dew-point. | Dew-point. | Tension of vapour. | | h m s | in. | feet | | | | | | | | | | | | | | | | | 6 16 10 | | | | | | | | | | | | | | | | | | | 16 30 | | | | | | | | | | | | | | | | | | | 17 0 47·3 | 18·95 | 12,530 | 29·0 | 23·0 | 6·0 | -105 | 59 | 14·4 | 32·5 | | | | | | | | | | | 18 0 | 18·85 | 12,670 | 29·9 | 23·2 | 6·7 | -102 | 55 | 13·6 | 33·4 | | | | | | | | | | | 18 30 | | | | | | | | | | | | | | | | | | | 19 0 46·6 | 18·71 | 12,830 | 29·0 | 22·7 | 6·3 | -102 | 57 | 13·6 | 32·6 | | | | | | | | | | | 19 40 | | | | | | | | | | | | | | | | | | | 20 0 45·9 | 18·66 | 12,950 | 30·0 | 23·3 | 6·7 | -103 | 56 | 13·9 | 33·6 | | | | | | | | | | | 20 30 | | | | | | | | | | | | | | | | | | | 21 0 45·0 | 18·55 | 13,110 | 29·9 | 23·2 | 6·7 | -103 | 56 | 13·9 | 33·6 | | | | | | | | | | | 21 40 | 18·49 | 13,170 | | | | | | | | | | | | | | | | | 22 0 | 18·46 | 13,200 | 26·7 | 21·3 | 5·4 | -101 | 61 | 13·3 | 30·4 | | | | | | | | | | | 23 0 44·5 | 18·26 | 13,500 | 27·4 | 21·9 | 5·5 | -104 | 61 | 14·1 | 31·1 | | | | | | | | | | | 24 0 | 18·11 | 13,720 | | | | | | | | | | | | | | | | | 25 0 43·0 | 17·97 | 13,920 | 26·7 | 20·1 | 6·6 | -89 | 54 | 9·9 | 29·9 | | | | | | | | | | | 25 40 | | | | | | | | | | | | | | | | | | | 26 0 42·6 | 17·85 | 14,080 | 25·6 | 19·3 | 6·3 | -87 | 55 | 9·3 | 29·5 | | | | | | | | | | | 26 30 | 17·78 | 14,220 | 27·7 | 20·5 | 7·2 | -88 | 51 | 9·6 | 31·6 | | | | | | | | | | | 27 0 | 17·77 | 14,180 | 24·2 | 18·5 | 5·7 | -87 | 58 | 9·3 | 28·1 | | | | | | | | | | | 27 40 | 17·75 | 14,210 | | | | | | | | | | | | | | | | | 28 0 | 17·62 | 14,440 | 26·1 | 20·3 | 5·8 | -95 | 59 | 11·7 | 30·1 | | | | | | | | | | | 28 30 | | | | | | | | | | | | | | | | | | | 29 0 | 17·45 | 14,640 | 22·9 | 18·3 | 4·6 | -94 | 65 | 11·4 | 26·9 | | | | | | | | | | | 29 30 | 17·39 | 14,750 | 22·5 | 18·3 | 4·2 | -87 | 62 | 9·3 | 26·5 | | | | | | | | | | | 30 0 | 17·35 | 14,790 | 21·9 | 18·9 | 3·0 | -106 | 76 | 14·6 | 25·9 | | | | | | | | | | | 30 30 | 17·33 | 14,820 | | | | | | | | | | | | | | | | | 31 0 | 17·31 | 14,870 | 23·1 | 19·3 | 3·8 | -103 | 72 | 13·9 | 27·2 | | | | | | | | | | | 32 0 | 17·26 | 14,930 | 21·9 | 18·5 | 3·4 | -102 | 74 | 13·6 | 26·0 | | | | | | | | | | | 32 30 | | | | | | | | | | | | | | | | | | | 33 0 | 17·16 | 15,090 | 22·4 | 19·1 | 3·3 | -106 | 75 | 14·6 | 26·5 | | | | | | | | | | | 34 0 | 17·12 | 15,130 | 21·6 | 18·9 | 2·7 | -108 | 79 | 15·1 | 25·8 | | | | | | | | | | | 35 0 | 17·12 | 15,130 | 20·6 | 18·2 | 2·4 | -107 | 81 | 14·9 | 24·8 | | | | | | | | | | | 35 30 | | | | | | | | | | | | | | | | | | | 36 0 | 17·17 | 15,060 | 20·8 | 18·3 | 2·5 | -107 | 80 | 14·9 | 25·1 | | | | | | | | | | | 36 30 | | | | | | | | | | | | | | | | | | | 37 0 | 17·13 | 15,110 | 20·8 | 17·9 | 2·9 | -103 | 78 | 13·9 | 25·1 | | | | | | | | | | | 38 0 | | | | | | | | | | | | | | | | | | | 39 0 | 16·92 | 15,410 | | | | | | | | | | | | | | | | | 39 30 | | | | | | | | | | | | | | | | | | | 40 0 | 16·61 | 15,900 | 19·0 | | | | | | | | | | | | | | | | 41 0 | 16·41 | 16,180 | 16·3 | 10·5 | 5·8 | -58 | 51 | 1·4 | 20·8 | | | | | | | | | | | 42 0 | 16·26 | 16,400 | 14·6 | 8·7 | 5·9 | -51 | 48 | 4·7 | 19·1 | | | | | | | | | | | 43 0 | 16·14 | 16,600 | 14·8 | 9·6 | 5·2 | -59 | 55 | 0·9 | 19·4 | | | | | | | | | | | 43 40 | | | | | | | | | | | | | | | | | | | 44 0 | 16·06 | 16,760 | 17·0 | 11·3 | 5·7 | -62 | 54 | 0·4 | 21·6 | | | | | | | | | | | 45 0 | 15·96 | 16,900 | 15·3 | 10·3 | 5·0 | -63 | 58 | 0·8 | 20·0 | | | | | | | | | | | 46 0 | 15·95 | 16,940 | 16·3 | 10·7 | 5·6 | -61 | 54 | 0·1 | 21·0 | | | | | | | | | | | 46 10 | | | | | | | | | | | | | | | | | | | 46 20 | | | | | | | | | | | | | | | | | | | 47 0 | 15·96 | 16,930 | 16·5 | 11·0 | 5·5 | -62 | 55 | 0·4 | 21·3 | | | | | | | | | | | 48 0 | 15·96 | 16,920 | 13·4 | 8·6 | 4·8 | -59 | 58 | 0·9 | 18·2 | | | | | | | | | | | 49 0 | 15·86 | 17,010 | 12·4 | 7·6 | 4·8 | -56 | 57 | 2·3 | 17·3 | | | | | | | | | | | 50 0 | 15·64 | 17,400 | 13·2 | 8·2 | 5·0 | -56 | 56 | 2·3 | 18·1 | | | | | | | | | | | 51 0 | 15·46 | 17,660 | 10·6 | 6·7 | 3·9 | -58 | 63 | 1·4 | 15·6 | | | | | | | | | | | 52 0 | | | | | | | | | | | | | | | | | | | 52 30 | | | | | | | | | | | | | | | | | | | 53 0 | 15·31 | 17,890 | 10·2 | 6·8 | 3·4 | -61 | 68 | 0·1 | 15·1 | | | | | | | | | | | 54 0 | 15·21 | 18,060 | 9·1 | 6·7 | 2·4 | -66 | 77 | 2·0 | 14·1 | | | | | | | | | | | 55 0 | 15·01 | 18,370 | 7·3 | 5·7 | 1·6 | -68 | 85 | 2·8 | 12·4 | | | | | | | | | | ### Table I. (Continued.) | Greenwich Mean Time | Barometer | Height above sea-level | Dry and Wet Thermometers, as aspirated | Dry and Wet Thermometers, free | Regnauld's Hygrometer | |---------------------|----------|-----------------------|----------------------------------------|-------------------------------|----------------------| | | Thermo. | Reading corrected | Dry. | Wet. | Diff. | in. | Relative humidity | Dew-point | Temp. | corrected | Dry. | Wet. | Diff. | Relative humidity | Dew-point | Temp. | | h m s | | | | | | in. | | Dew-point | | | | | | | Dew-point | | | August 26, 1852 | | | | | | | | in. | | | | | | | in. | | | 6 56 0 | | | 14·91 | | 9·5 | 6·5 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 56 15 | | | 14·88³ | | 8·3 | 6·6 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 57 0 | | | 14·76 | | 9·0 | 6·7 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 57 30 | | | 14·65³ | | 8·3 | 6·3 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 58 0 | | | 14·66 | | 7·5 | 7·0 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 58 30 | | | 14·68 | | 7·0 | 6·3 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 59 0 | | | 14·61 | | 6·3 | 6·3 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 59 9 | | | 14·66 | | 5·5 | 4·8 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 6 0 | | | 14·69 | | 4·8 | 4·1 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | August 27, 1852 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 52 0 | | | 29·73 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 52 30 | | | 29·34 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 49 0 | | | 29·97 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 50 0 | | | 28·82 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 50 30 | | | 28·50 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 40 0 | | | 27·61 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 50 0 | | | 27·25 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 53 0 | | | 26·70 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 53 30 | | | 27·10 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 55 0 | | | 27·0 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 56 0 | | | 26·67 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 56 30 | | | 26·52 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 58 0 | | | 26·19 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | October 21, 1852 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 50 5 | | | 25·96 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 51 0 | | | 27·10 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | --- **Note:** The image contains detailed weather observations including barometric pressure, thermometers readings, dry and wet bulb temperature differences, tension of vapour, dew point, humidity, and corrected dry- and wet- bulb thermometers readings. --- **Legend:** - Greenwich Mean Time - Barometer Readings and Heights - Dry and Wet Thermometers, Aspirated - Temperature Corrections - Dew Points --- **Source:** Observations in Four Balloon Ascents by Lady Evans. ## Table I. (Continued.) | Greenwich Mean Time | Barometer | Height above sea-level | Dry and Wet Thermometers, aspirated | Temperature corrected for change | Dry and Wet Thermometers, free | Regnauld's Hygrometer | |---------------------|-----------|------------------------|-------------------------------------|-------------------------------|-------------------------------|-----------------------| | | | | Dry. Wet. Diff. Tension of vapour. Relative humidity Dew-point. | | Dry. Wet. Diff. Tension of vapour. Relative humidity Dew-point. | Dew-point. Tension of vapour. | | h m s | in. | feet | | | | | | 3 19 0 | 20-22 | 10,650 | 3°7 2°6 6°1 -142° 72° 2°6 2°3 | | | | | 19 30 | 3°1-2 | 2°7-0 4°2 -138° 71° 2°1-8 3°1-8 | | | | | | 20 0 | 20-03 | 10,900 | 3°1-1 2°6-2 4°9 -129° 67° 2°0-0 3°1-8 3°1-0 2°6-3 4°7 -130° 68° 2°0-2 | | | | | 21 0 | 19-85 | 11,130 | 2°9-8 2°5-7 4°1 -131° 71° 2°0-4 3°0-5 3°1-6 2°6-8 4°8 -132° 67° 2°0-6 | | | | | 22 0 | 19-63 | 11,420 | 2°9-4 2°5-2 4°2 -128° 71° 1°9-8 3°0-1 3°0-4 2°5-9 4°5 -130° 69° 2°0-2 | | | | | 23 0 | 19-41 | 11,700 | 2°7-8 2°4-1 3°7 -126° 73° 1°9-3 2°8-6 2°9-2 2°4-7 4°5 -123° 68° 1°8-7 | | | | | 24 0 | 19-23 | 11,940 | 2°6-8 2°3-2 3°6 -121° 73° 1°8-2 2°7-6 2°8-2 2°3-8 4°4 -119° 70° 1°7-8 | | | | | 25 0 | 19-10 | 12,130 | 2°6-8 2°2-6 4°2 -115° 69° 1°6-8 2°7-6 2°8-2 2°3-8 4°4 -119° 70° 1°7-8 | | | | | 26 0 | 19-04 | 12,320 | 2°5-9 | | | | | 27 0 | 18-85 | 12,450 | 2°4-9 | | | | | 28 0 | 18-73 | 12,630 | 2°5-9 | | | | | 28 30 | 2°5-8 | 2°2-0 3°8 -114° 71° 1°6-6 2°6-7 | | | | | | 29 0 | 18-72 | 12,640 | 2°5-7 2°2-0 3°7 -115° 72° 1°6-8 2°6-7 2°7-6 2°4-3 3°3 -130° 76° 2°0-2 | | | | | 29 30 | 2°6-0 | 2°2-0 4°0 -113° 70° 1°6-4 2°7-0 | | | | | | 30 0 | 2°6-9 | 2°3-0 3°9 -119° 72° 1°7-8 2°7-9 2°7-7 2°4-1 3°6 -127° 74° 1°9-5 1°9-0 -124° | | | | | 30 25 | 18-85 | 12,470 | 2°6-5 2°3-4 3°1 -126° 77° 1°9-3 2°7-5 2°7-8 2°4-2 3°6 -127° 74° 1°9-5 1°8-0 -120° | | | | | 31 25 | 19-15 | 12,050 | 2°6-5 2°3-4 3°1 -126° 77° 1°9-3 2°7-5 2°7-8 2°4-2 3°6 -127° 74° 1°9-5 1°8-0 -120° | | | | | 33 50 | 19-97 | 10,960 | 2°9-7 2°5-7 4°0 -131° 71° 2°0-4 3°0-8 | | | | | 36 0 | 20-67 | 10,070 | 3°3-4 2°9-2 4°2 -150° 72° 2°4-1 3°4-6 | | | | | 37 30 | 21-24 | 9,360 | 3°5-5 3°0-2 5°3 -149° 66° 2°3-9 3°6-7 3°6-2 3°1-3 4°9 -159° 69° 2°5-7 | | | | | 38 0 | 21-50 | 9,040 | 3°6-5 3°0-2 6°3 -140° 60° 2°2-2 3°7-7 | | | | | 39 0 | 43°6 | 21-81 | 8,660 | | | | | 39 30 | 21-92 | 8,530 | 3°8-4 3°1-0 7°4 -136° 55° 2°1-4 3°9-7 | | | | | 40 0 | 22-05 | 8,380 | 3°9-3 3°1-2 8°1 -132° 51° 2°0-6 4°0-6 | | | | | 41 0 | 22-25 | 8,140 | 4°0-8 3°1-5 9°3 -125° 46° 1°9-1 4°2-1 | | | | | 42 30 | 44°5 | 22-46 | 7,900 | | | | | 43 30 | 22-55 | 7,800 | 4°3-2 3°5-1 8°1 -153° 52° 2°4-7 4°4-6 4°3-4 3°7-7 5°7 -195° 66° 3°1-4 | | | | | 45 0 | 22-49 | 7,870 | 4°2-5 3°5-2 7°3 -160° 55° 2°5-9 4°3-9 | | | | | 46 0 | 22-40 | 7,970 | 4°2-4 3°4-7 7°7 -153° 53° 2°4-7 4°3-8 | | | | | 48 0 | 23-31 | 8,090 | 4°2-9 3°4-7 8°2 -149° 51° 2°3-9 4°4-4 | | | | | 49 0 | 23-34 | 8,050 | 4°3-7 3°6-3 7°4 -169° 56° 2°7-4 4°5-2 4°3-1 3°5-7 7°4 -164° 56° 2°6-6 | | | | | 50 0 | 22-55 | 7,810 | 4°4-3 3°5-9 8°4 -156° 51° 2°5-2 4°5-7 4°4-6 3°7-3 7°3 -177° 57° 2°8-7 | | | | | 53 0 | 23-42 | 6,780 | 4°6-1 3°9-8 6°3 -206° 63° 3°2-9 4°7-7 4°6-6 4°0-6 6°0 -216° 65° 3°4-3 | | | | | 54 0 | 23-62 | 6,550 | 4°6-4 4°1-2 5°2 -229° 69° 3°5-9 4°8-0 | | | | | 54 20 | 23-70 | 6,450 | | | | | | 57 30 | 23-74 | 6,400 | 4°4-7 4°0-8 3°9 -236° 76° 3°6-8 4°6-5 | | | | | 58 30 | 24-62 | 5,420 | 4°6-7 4°2-4 4°3 -247° 74° 3°8-1 4°8-5 | | | | | 4 1 30 | 24-62 | 5,420 | 4°6-7 4°2-4 4°3 -247° 74° 3°8-1 4°8-5 | | | | | 3 30 | 25-51 | 4,460 | 4°9-4 4°5-6 3°8 -284° 78° 4°2-1 5°1-3 | | | | | 4 0 | 25-75 | 4,210 | | | | | | 5 0 | 26-12 | 3,820 | 5°0-6 4°7-6 3°0 -314° 82° 4°5-0 5°2-5 5°0-6 4°8-1 2°5 -325° 85° 4°6-0 | | | | | 5 45 | 26-47 | 3,450 | 5°0-6 4°8-6 2°0 -335° 88° 4°6-8 5°2-5 5°0-6 4°8-7 1°9 -338° 89° 4°7-1 | | | | | 6 30 | 51°0 | 26-73 | 5°0-2 4°8-7 1°5 -342° 91° 4°7-5 5°2-1 | | | | | 8 0 | 27-03 | 2,880 | 5°0-1 4°9-1 1°0 -352° 94° 4°8-3 5°2-1 | | | | --- **October 21, 1852.** **November 10, 1852.** ## Observations in Four Balloon Ascents ### Table I (Continued) | Greenwich Mean Time | Barometer | Height above sea-level | Dry and Wet Thermometers, aspirated | Temperature corrected for change | Dry and Wet Thermometers, free | Regnault's Hygrometer | |---------------------|-----------|------------------------|------------------------------------|---------------------------------|-------------------------------|----------------------| | | | feet | Dry. | Wet. | Diff. | Tension of vapour | Relative humidity | Dew-point | Temperature corrected for change | Dry. | Wet. | Diff. | Tension of vapour | Relative humidity | Dew-point | Tension of vapour | | h m s | in. | | | | | | | | | | | | | | | | | 23 10 | 24·17 | 5,880 | 34·7 | 33·4 | 1·3 | 1·97 | 90 | 31·7 | 34·7 | | | | | | | | | 34 0 | 44·3 | 6,140 | 35·6 | 31·4 | 4·2 | 1·60 | 71 | 25·9 | 35·6 | | | | | | | | | 34 30 | 23·76 | 6,350 | 35·8 | 30·8 | 5·0 | 1·50 | 66 | 24·1 | 35·8 | | | | | | | | | 35 0 | 23·63 | 6,500 | 35·8 | 30·8 | 5·0 | 1·50 | 66 | 24·1 | 35·8 | | | | | | | | | 35 30 | 23·45 | 6,700 | 35·6 | 31·4 | 4·2 | 1·61 | 76 | 27·1 | 34·7 | | | | | | | | | 36 30 | 43·0 | 7,070 | 34·7 | 31·2 | 3·5 | 1·67 | 76 | 27·1 | 34·7 | | | | | | | | | 37 30 | 22·72 | 7,530 | 33·9 | 31·6 | 2·3 | 1·78 | 84 | 28·9 | 33·9 | | | | | | | | | 38 0 | 32·7 | 8,030 | 32·7 | 31·0 | 1·7 | 1·79 | 88 | 29·0 | 32·7 | | | | | | | | | 38 30 | 22·29 | 8,420 | 32·5 | 31·4 | 1·1 | 1·87 | 92 | 30·2 | 32·5 | | | | | | | | | 39 0 | 21·97 | 8,890 | 31·4 | 29·7 | 1·7 | 1·71 | 88 | 27·7 | 31·4 | | | | | | | | | 40 0 | 21·58 | 9,510 | 29·8 | 27·2 | 2·6 | 1·49 | 81 | 23·9 | 29·8 | | | | | | | | | 41 0 | 40·5 | 9,970 | 29·5 | 26·2 | 3·3 | 1·38 | 76 | 21·8 | 29·5 | | | | | | | | | 42 0 | 20·71 | 10,630 | 26·9 | 24·2 | 2·7 | 1·32 | 79 | 20·6 | 26·9 | | | | | | | | | 43 0 | 20·17 | 11,310 | 24·9 | 22·4 | 2·5 | 1·24 | 80 | 18·9 | 24·9 | | | | | | | | | 44 0 | 19·65 | 12,500 | 20·3 | (32) | | | | | 20·3 | | | | | | | | | 45 30 | 18·74 | 13,080 | 17·4 | | | | | | 17·4 | | | | | | | | | 46 30 | 18·30 | 13,650 | 16·3 | | | | | | 16·3 | | | | | | | | | 47 0 | 17·90 | 13,860 | 15·9 | 12·4 | 3·5 | 0·76 | 68 | 5·8 | 15·9 | | | | | | | | | 47 30 | 17·75 | 14,540 | 13·4 | 8·9 | 4·5 | 0·60 | 59 | 0·5 | 13·4 | | | | | | | | | 49 0 | 16·66 | 15,820 | 12·8 | 8·1 | 4·7 | 0·57 | 58 | 1·8 | 12·8 | | | | | | | | | 49 30 | 16·44 | 16,150 | 11·9 | 10·3 | 1·6 | 0·81 | 84 | 7·4 | 11·9 | | | | | | | | | 50 30 | 15·96 | 16,580 | 11·9 | 10·3 | 1·6 | 0·81 | 84 | 7·4 | 11·9 | | | | | | | | | 52 0 | 15·28 | 17,620 | 7·0 | 5·6 | 1·4 | 0·68 | 85 | 2·8 | 7·0 | | | | | | | | | 52 30 | 14·72 | 18,520 | 3·8 | 1·3 | 2·5 | 0·52 | 74 | 4·2 | 3·8 | | | | | | | | | 55 0 | 14·44 | 18,990 | 2·7 | 0·6 | 2·1 | 0·52 | 77 | 4·2 | 3·8 | | | | | | | | | 56 0 | 14·24 | 19,330 | 1·5 | 0·1 | 1·6 | 0·53 | 82 | 3·7 | 1·5 | | | | | | | | | 57 0 | 14·01 | 19,730 | 0·4 | 0·5 | 0·9 | 0·56 | 90 | 2·3 | 0·4 | | | | | | | | | 58 0 | 14·04 | 19,690 | 1·0 | 0·2 | 0·8 | 0·58 | 91 | 1·4 | 1·0 | | | | | | | | | 59 0 | 14·20 | 19,400 | 1·5 | 0·0 | 1·5 | 0·54 | 83 | 3·2 | 1·5 | | | | | | | | | 3 1 0 | 14·78 | 18,430 | 4·4 | 0·9 | 3·5 | 0·46 | 64 | 7·4 | 4·4 | | | | | | | | | 2 0 | 18·2 | 18,110 | 3·4 | 0·2 | 3·6 | 0·42 | 60 | 9·7 | 3·4 | | | | | | | | | 3 30 | 14·94 | 18,130 | 3·4 | 1·8 | 5·2 | 0·31 | 44 | 18·0 | 3·4 | | | | | | | | | 5 0 | 14·60 | 18,700 | 2·2 | 2·1 | 4·3 | 0·35 | 53 | 14·0 | 2·2 | | | | | | | | | 6 0 | 14·40 | 19,020 | 0·5 | | | | | | 0·5 | | | | | | | | | 7 0 | 14·0 | 19,560 | 1·3 | | | | | | 1·3 | | | | | | | | | 8 30 | 11·5 | 20,430 | 2·3 | | | | | | 2·3 | | | | | | | | | 9 0 | 13·45 | 20,650 | 5·1 | | | | | | 5·1 | | | | | | | | | 10 30 | 13·02 | 21,380 | 9·3 | | | | | | 9·3 | | | | | | | | | 12 0 | 12·65 | 22,110 | 9·6 | | | | | | 9·6 | | | | | | | | | 13 0 | 12·51 | 22,370 | 10·5 | | | | | | 10·5 | | | | | | | | | 14 30 | 12·40 | 22,640 | 8·9 | | | | | | 8·9 | | | | | | | | | 15 0 | 12·24 | 22,930 | 6·5 | | | | | | 6·5 | | | | | | | | | 16 0 | 12·24 | 22,930 | 5·3 | | | | | | 5·3 | | | | | | | | | 17 0 | 12·94 | 21,640 | | | | | | | | | | | | | | | | 19 0 | 12·94 | 21,640 | | | | | | | | | | | | | | | § 5. Variation of Temperature with Height. The observations of temperature given in the preceding table, with the corresponding heights, have been divided into groups, each group being composed of the observations within 1000 feet*. The numbers employed are those in column 11 of the table, which have been corrected for the change occurring in the temperature during the continuance of the experiments, as given by corresponding observations at the earth’s surface. This correction is very probably inaccurate to some extent; but our information is as yet so imperfect with regard to the diurnal variations of temperature in the upper parts of the atmosphere, that no other course has appeared open to me. Any error arising from this cause is probably small in any of the series now under consideration, with the exception perhaps of August 26, when the hourly changes, as well as the time occupied in the ascent, were considerable. These groups are contained in the following table: Table II.—Means of Groups of the Observations of Temperature at different heights in the four Balloon Ascents of 1852, with the differences between the observed temperatures and those calculated by equations (1.) and (2.) from each whole series, and from the adopted divisions of each series. | Date | No. of obs. | Height | Temperature | Whole Series | Lower Division | Upper Division | |------------|-------------|--------|-------------|--------------|----------------|---------------| | | | | | By eq. (1.) | By eq. (2.) | By eq. (1.) | | August 17 | (1) | feet | | | | | | | (120) | (71·2) | −1·4 | +1·3 | 0·0 | (−5·1) | | | 1 | 2,440 | 62·8 | −2·4 | −1·4 | (−5·6) | | | 1 | 3,460 | 59·2 | −2·8 | −2·4 | (−5·8) | | | 1 | 4,110 | 58·1 | −1·9 | −1·7 | (−4·7) | | | 1 | 5,880 | 57·8 | +3·2 | +2·8 | (+0·9) | | | 3 | 6,800 | 54·0 | +3·2 | +1·6 | (+0·2) | | | 5 | 7,530 | 51·4 | +2·0 | +1·1 | (+6·9) | | | 8 | 8,550 | 49·0 | +2·7 | +1·7 | (+8·1) | | | 7 | 9,470 | 44·4 | +1·0 | −0·1 | (+6·9) | | | 4 | 10,680 | 40·4 | +0·7 | −0·4 | (+7·2) | | | 4 | 11,620 | 37·2 | +0·4 | −0·6 | | | | 8 | 12,250 | 34·9 | +0·1 | −0·9 | | | | 3 | 13,480 | 30·8 | −0·2 | −0·9 | | | | 4 | 14,550 | 27·0 | −0·7 | −1·1 | | | | 6 | 15,510 | 24·4 | −0·3 | −0·4 | | | | 10 | 16,600 | 20·6 | −0·8 | −0·4 | | | | 6 | 17,440 | 19·6 | +0·9 | +1·6 | | | | 6 | 18,490 | 15·0 | −0·5 | +0·9 | | | | 8 | 19,320 | 10·5 | −2·4 | −0·5 | | * The third group of October 21 extends only from 2000 to 2670 feet; the two observations between the latter height and 3000 feet, showing a marked change which refers them more intimately to the succeeding group. The lowest group in each series depends solely upon observations taken in the car, with the exception of that of August 17, when no observations having been recorded below 2000 feet, the general temperature at the earth has been adopted as the first result. ## OBSERVATIONS IN FOUR BALLOON ASCENTS. ### TABLE II. (Continued.) | Date | No. of obs. | Height. | Temperature. | Whole Series | Lower Division | Upper Division | |---------------|-------------|---------|--------------|--------------|----------------|----------------| | | | feet. | | By eq. (1.) | By eq. (2.) | By eq. (1.) | | August 26 | 3 | 700 | 64·8 | +1·6 | +2·3 | −0·2 | | | 2 | 1,380 | 62·8 | +0·8 | +1·4 | −0·4 | | | 5 | 2,480 | 59·1 | +0·6 | +0·9 | +0·4 | | | 4 | 3,390 | 55·7 | −0·4 | −0·3 | +0·0 | | | 4 | 4,430 | 51·7 | −1·7 | −1·7 | 0·0 | | | 3 | 5,620 | 48·0 | −2·3 | −2·5 | +0·5 | | | 3 | 6,350 | 44·3 | −4·1 | −4·3 | −0·6 | | | 3 | 7,390 | 41·9 | −3·7 | −4·1 | (+ 0·7) | | | 3 | 8,730 | 42·9 | +0·8 | +0·4 | (+ 6·4) | | | 10 | 9,510 | 42·3 | +2·2 | +1·8 | (+ 8·6) | | | 20 | 10,590 | 41·0 | +3·7 | +3·3 | (+11·1) | | | 25 | 11,630 | 37·4 | +2·9 | +2·5 | (+11·2) | | | 46 | 12,490 | 34·0 | +1·7 | +1·4 | (+10·9) | | | 5 | 13,350 | 31·9 | +1·9 | +1·6 | (+17·1) | | | 11 | 14,500 | 28·1 | +1·1 | +1·0 | | | | 7 | 15,200 | 25·3 | +0·1 | +0·1 | | | | 8 | 16,700 | 20·2 | −1·1 | −0·8 | | | | 4 | 17,460 | 16·5 | −2·8 | −2·3 | | | | 8 | 18,750 | 14·5 | −1·4 | −0·6 | | | October 21 | 4 | 690 | 55·5 | −1·4 | +2·1 | +0·2 | | | 3 | 1,480 | 52·1 | −3·1 | −1·0 | −0·4 | | | 3 | 2,360 | 49·5 | −3·6 | −3·1 | +0·2 | | | 10 | 3,330 | 51·4 | +0·5 | −0·3 | (+ 5·5) | | | 6 | 4,420 | 51·7 | +3·3 | +1·5 | (+ 9·8) | | | 6 | 5,530 | 48·9 | +3·1 | +0·6 | (+10·9) | | | 7 | 6,580 | 46·5 | +3·1 | +0·5 | (+12·3) | | | 8 | 7,770 | 44·1 | +3·4 | +1·1 | (+14·1) | | | 9 | 8,280 | 41·7 | +2·2 | +0·2 | (+13·6) | | | 6 | 9,380 | 36·9 | −0·1 | −1·1 | (+12·7) | | | 8 | 10,520 | 32·7 | −1·7 | −1·2 | | | | 4 | 11,550 | 29·2 | −2·8 | −0·5 | | | | 9 | 12,430 | 27·0 | −3·0 | +1·1 | | | November 10 | 2 | 410 | 48·9 | −0·1 | +4·7 | +0·2 | | | 4 | 1,500 | 44·3 | −2·0 | +1·4 | −0·3 | | | 1 | 2,760 | 39·6 | −3·5 | −1·6 | −0·2 | | | 2 | 3,430 | 37·6 | −3·9 | −2·6 | +0·3 | | | 3 | 4,490 | 35·5 | −3·3 | −3·0 | (+ 1·2) | | | 2 | 5,620 | 34·2 | −1·8 | −2·4 | (+ 5·1) | | | 4 | 6,420 | 35·7 | +1·7 | +0·5 | (+ 9·6) | | | 3 | 7,460 | 33·8 | +2·4 | +0·7 | (+11·6) | | | 3 | 8,440 | 32·2 | +3·2 | +1·1 | (+13·7) | | | 2 | 9,740 | 29·6 | +3·9 | +1·3 | | | | 1 | 10,630 | 26·9 | +3·4 | +0·7 | | | | 1 | 11,300 | 24·9 | +3·1 | +0·3 | | | | 1 | 12,500 | 20·3 | +1·5 | −1·2 | | | | 3 | 13,530 | 16·5 | +0·3 | −2·3 | | | | 2 | 15,650 | 13·1 | +2·1 | +0·4 | | | | 1 | 16,580 | 11·9 | +3·3 | +2·0 | | | | 1 | 17,620 | 7·0 | +1·0 | +0·4 | | | | 6 | 18,480 | 3·3 | −0·6 | −0·4 | | | | 6 | 19,460 | 0·6 | −0·8 | +0·2 | | | | 2 | 20,540 | −3·7 | −2·4 | −0·3 | | | | 2 | 21,510 | −7·3 | −3·6 | −0·4 | | | | 3 | 22,370 | −9·7 | −3·9 | +0·5 | | In order to deduce from these numbers an approximation to the normal progression of temperature, freed from accidental irregularities, each series was in the first instance arranged in equations of the form— \[ T = X + YH \] \( T \) being the observed temperature at the height \( H \); \( Y \) the change in degrees of temperature due to 1000 feet of height; and \( X \) the temperature at the level of the sea, which, with the addition of the quantity \( YH \), would best represent the observed temperatures throughout the series, on the supposition of the change being uniform with the height. \( X \) and \( Y \) were eliminated by the method of least squares, and the following values obtained for the different series: | Aug. 17 | Aug. 26 | Oct. 21 | Nov. 10 | |---------|---------|---------|---------| | \( X = \) | 72°76 | 64°98 | 58°49 | 50°02 | | \( Y = \) | -3°097 | -2°617 | -2°291 | -2°496 | | Mean error | 1°72 | 2°16 | 2°65 | 2°56 | On the supposition that the rate of change is not constant, but that it varies with the height, the following interpolating equation was employed, \[ T = x + yH + zH^2 + &c., \] omitting higher powers of \( H \) than the second. When the same method of elimination was adopted, the following values were found: | Aug. 17 | Aug. 26 | Oct. 21 | Nov. 10 | |---------|---------|---------|---------| | \( x = \) | 70°17 | 64°11 | 53°36 | 44°69 | | \( y = \) | -2°363 | -2°346 | +0°1132 | -1°095 | | \( z = \) | -0°03613 | -0°01424 | -1°868 | -0°06070 | | Mean error | 1°30 | 2°13 | 1°35 | 1°71 | In Table II. will be found the differences between the observed temperatures, and those resulting from the two forms of equation employed. The progress of those differences in each series seems to follow a distinct law; there being in all cases a maximum of negative differences at a short distance from the earth, varying from about 2500 feet on October 21, to 6000 feet on August 26, followed also in each by a maximum of positive differences at an additional height of 3000 to 5000 feet. This peculiar departure from a regular progression will be distinctly traced in the projected results (Plates XIX.—XXII.). It is there seen, in all the four series, that after a steady decrease of the temperature in the lower portion of the curve, this decrease becomes arrested, and, for a space of about 2000 feet, the temperature remains almost constant, or even increases by a small amount; the decrease being afterwards resumed and continued, without much variation, throughout the upper portion of the curve. In the series of August 17 and 26 this fact is strikingly coincident with a large and abrupt diminution in the amount of aqueous vapour; the same coincidence being exhibited, in a less marked manner, on November 10. On October 21, the departure from a uniform decrease is very decidedly shown in connection with the stratum of dense cloud passed through. The temperature had been uniformly decreasing until the thick cloud was reached, when a decided rise commenced, which continued through the cloud, and for a space of about 600 feet above it; after which height the decrease was resumed, at first slowly, and afterwards with more rapidity. The disturbance in the variation of the temperature now noticed, is in each series exhibited in such a systematic manner, that the hypothesis of a regular progression at all heights can scarcely be maintained. In order therefore to arrive at some approximate value of the normal variation of temperature in the atmosphere, it appears necessary to make abstraction of the disturbing cause. This I have endeavoured to do by dividing each series into two divisions; 1st, between the earth and the height where the diminution of temperature appears to be arrested; 2nd, above the point where the regular diminution of temperature seems to be resumed, omitting the space which is under the influence of the disturbance. The divisions adopted for the four series are as follows: | Aug. 17 | Aug. 26 | Oct. 21 | Nov. 10 | |---------|---------|---------|---------| | Feet | Feet | Feet | Feet | | Lower division | 0 to 4000 | 0 to 7000 | 0 to 2700 | 0 to 4000 | | Upper division | 7000 to 20,000 | 10,000 to 19,000 | 5000 to 13,000 | 9000 to 23,000 | These partial series have been examined by the same methods as the entire series; the number of groups in the lower division being, however, with the exception of August 26, too small to admit of the application with any advantage of equation (2.). The results for the different series are as follows: | | By Equation (1.) | By Equation (2.) | |--------|------------------|------------------| | | x | Y | Mean error. | x | y | z | Mean error. | | Aug. 17 | Lower division | 71°62 | −3°598 | 0°00 | 79°17 | −3°771 | +0°01484 | 0°71 | | | Upper division | 76°68 | −3°371 | 0°73 | −2°969 | −0°08220 | +0°02552 | 0°30 | | Aug. 26 | Lower division | 67°46 | −3°549 | 0°39 | 66°75 | −4°104 | +0°01119 | 0°80 | | | Upper division | 76°36 | −3°355 | 0°60 | 81°68 | −1°516 | −0°04791 | 1°02 | | Oct. 21 | Lower division | 57°77 | −3°581 | 0°26 | 67°81 | −3°162 | −0°01119 | 0°80 | | | Upper division | 68°77 | −3°376 | 0°82 | −1°516 | −0°04791 | 1°02 | | Nov. 10 | Lower division | 50°21 | −3°760 | 0°26 | 48°05 | −1°516 | −0°04791 | 1°02 | | | Upper division | 59°45 | −3°046 | 1°22 | −1°516 | −0°04791 | 1°02 | The values of the constants in equation (2.), deduced from the higher divisions, show that, in the two series of August 17 and 26, the temperature decreases less rapidly as we ascend; whilst the values for October 21 and November 10 indicate a contrary result. The value of the second term (z) is, with the exception of the series of November 10, very small, and the amounts of the mean errors show that the observations are little better represented than by the single constant of equation (1.). MDCCCLIII. On the whole, we are scarcely at liberty to conclude from these results that the progress of the temperature, when free from disturbing influences, is other than uniform with the height. Confining our attention now to the results deduced by equation (1.), we infer from them that in each series the rate of decrease of temperature, below the stratum where the disturbing influence exists, is greater than above that stratum; the ratio of the rate of decrease in the lower division to that in the higher, being— On Aug. 17, 1°067; on Aug. 26, 1°058; on Oct. 21, 1°061; and on Nov. 10, 1°234. If, in order to obtain the mean rate of decrease of temperature in the atmosphere, freed from disturbing causes, we allow to the lower and upper series values proportional to the spaces within which the observations for each division occur, we have the following numbers representing the decrease of temperature for 1000 feet of height: | Date | Rate of Decrease | |----------|------------------| | Aug. 17 | 3°434 | | Aug. 26 | 3°440 | | Oct. 21 | 3°431 | | Nov. 10 | 3°205 | the values for the first three series being almost identical; that for the fourth differing from them by \( \frac{1}{15} \)th of the whole. It may be convenient to give here the results for the rate of diminution of temperature obtained by different methods, expressed in the form usually adopted by meteorologists, viz. the height in feet equivalent to a decrease of one degree Fahrenheit. | Method | Aug. 17 | Aug. 26 | Oct. 21 | Nov. 10 | |---------------------------------|---------|---------|---------|---------| | From the whole series | 322°9 | 382°0 | 436°5 | 400°6 | | From first and last groups only | 316°3 | 358°8 | 411°9 | 374°7 | | From lower division | 277°9 | 281°8 | 279°3 | 266°0 | | From upper division | 296°5 | 298°1 | 296°2 | 328°3 | | Mean of two divisions | 292°0 | 290°7 | 291°5 | 312°0 | The amount of distortion in the curve representing the diminution of temperature, produced by the disturbing influence which has been noticed, may be approximately stated at 7° on Aug. 17; 10°\( \frac{1}{2} \) on Aug. 26; 11°\( \frac{1}{2} \) on Oct. 21, and 12° on Nov. 10. § 6. Variation of the Hygrometric Condition of the Air. As the amount of aqueous vapour in the air must necessarily decrease with the temperature, even although the proportion to the whole capacity of the air for moisture should remain constant, the changes at different heights may probably be most conveniently studied by examining the results for the "Relative Humidity," or the proportion which the amount of vapour present in the air bears to that which it would contain were it completely saturated. Since these changes do not, as in the case of temperature, appear to follow any regular course from which normal results might be derived, I shall here only state briefly the most prominent peculiarities pre- sented by each series, referring for further information to the table of observations and to the projected results. August 17.—We see by the curve of relative humidity for this day, that, from the earth's surface to the height of about 4000 feet, the humidity slightly increased; the presence of a considerable quantity of moisture being also shown by the existence of a partial stratum of cloud at the height of about 2500 feet. Between the heights of 4000 and 5880 the humidity decreased with great rapidity from about 85 to less than 35. For a considerable space little alteration took place, with the exception of a sudden increase at the height of about 9000 feet, which was confined to a stratum of not more than 400 feet; but as the evidence of its existence depends upon only one or two observations it may perhaps be doubtful. From 10,000 feet to 12,300, the humidity gradually increased to about 90, which value it retained very constantly through fully 4000 feet. After 16,500 feet there were considerable irregularities, there being however a comparatively dry stratum between 18,000 and 19,000 feet, which was followed by a decided increase in the humidity. These indications agree well with what is stated in § 3. with regard to the occasional existence of cloud above the height of 13,000 feet, and with the fact that at the highest point reached a mass of cloud was seen at a short distance above. In this series we can trace the existence of two distinct strata of moist air, besides a third, which undoubtedly existed at a greater height, but which was not quite reached. August 26.—As on the first ascent, the humidity steadily increased from the earth's surface. Between the heights of 7200 and 8950 feet it also rapidly diminished from 92 to 26. For some distance the variations were no greater than might be supposed to arise from uncertainty of observation in such extreme circumstances. It will be remarked, on examining the curve of the tension of vapour, that whilst the indications of Regnault's hygrometer did not differ much from those of the wet thermometer at the height of about 11,000 feet, the difference became considerable at about 12,000 or 13,000 feet; thus rendering it probable that at the latter heights the relative humidity, as deduced from the dry and wet thermometers, was too great. The general accordance between the two hygrometers was however nearly restored at about 15,000 feet, confirming the rise which there took place in the amount of vapour. We may therefore consider that there was little change in the humidity from 9000 to 14,000 feet, a decided increase having however occurred at 15,000 feet, followed by a diminution till 16,400 feet; an increase having been again indicated in the remainder of the curve. The principal stratum of vapour on this day extended from the earth to 7200 feet, a second and perhaps a third of smaller thickness existing at 15,000 and 18,000 feet. October 21.—The amount of moisture in the air on this occasion was considerable. The relative humidity increased as we left the earth, at first slowly till the height of 2000 feet, when irregular masses of cloud became frequent, and afterwards with more rapidity, till within the principal cloudy mass, at a height of 3450 feet, it attained the point of complete saturation. After leaving the cloud the humidity diminished steadily but not very rapidly till 5300 feet, where a slight rise commenced, continuing till 6700 feet; it then decreased till 8300 feet, when it rose again and remained nearly constant at 70 for the last 3000 feet of the ascent. The changes occurring in this series were neither to the same extent nor so abrupt in their character as those shown in the first two. November 10.—The humidity, again, as in all the previous series, increased from the earth to the first cloud, which was at a low elevation and of but little density; upon leaving it, at about 1900 feet, a slight depression took place. Immediately above this low cloud a different current of air existed, shortly after entering which the humidity again increased until, in the second cloud, it became nearly complete; the decrease, after leaving the cloud at 5000 feet, becoming rapid and attaining a minimum at 6500 feet. A second well-defined maximum was reached at 8300 feet, followed at 10,000 feet by a secondary minimum. The humidity diminished on the whole till about 15,800 feet, when a sudden increase commenced, which continued from 16,500 to 17,600 feet, followed by an equally sudden decrease at 18,000 feet, the humidity subsequently increasing. The fluctuations in this series were numerous, there having been no fewer than four or perhaps five different strata of vapour. § 7. General Remarks. The principal results deduced from the experiments described may be thus generally stated. The temperature of the air decreases uniformly with the height above the earth's surface, until at a certain elevation, varying on different days, the decrease is arrested, and for a space of from 2000 to 3000 feet the temperature remains nearly constant, or even increases by a small amount; the regular diminution being afterwards resumed and generally maintained, at a rate slightly less rapid than in the lower part of the atmosphere, and commencing from a higher temperature than would have existed but for the interruption noticed. This interruption in the decrease of temperature is accompanied by a large and abrupt fall in the temperature of the dew-point, or by actual condensation of vapour, from which it may be inferred that the disturbance in the progression of temperature arises from a development of heat in the neighbourhood of the plane of condensation. The subsequent falls in the temperature of the dew-point are generally of an abrupt character, and corresponding interruptions in the decreasing progression of temperature are sometimes distinguishable, but in a less degree; as might indeed be expected from the fact, that at lower temperatures the variations in the absolute amount of aqueous vapour are necessarily smaller, and their thermic effects consequently diminished. Dr. Miller's Analysis of Air collected in the Ascents. "King's College, London, 5 May, 1853. "My dear Sir,—The following particulars of my examinations of some of the specimens of air collected by Mr. Welsh in the course of the balloon ascents made under the superintendence of the Kew Committee of the British Association, may not be unacceptable to the Fellows of the Royal Society as supplementary to a part of Mr. Welsh's report and observations. "The samples of air collected upon the 26th of August appear to have been taken in the most unexceptionable manner, and it was upon these only that my experiments were made. The recipients for the air were wide glass tubes, about 5 cubic inches in capacity, to each of which a portion of barometric tubing, 3 or 4 inches in length, was attached, as a neck that might receive a cap and stopcock, and which would admit also of being hermetically sealed afterwards by the blowpipe. Two of these tubes were furnished with excellent stopcocks, and were found able to support without leakage for twenty-four hours the exhaustion obtained by an air-pump, the gauge of which indicated a pressure of 0·5 inch. "Having been thus tested they were exhausted to this extent immediately before the ascent took place, and were filled with the specimens to be examined by simply opening and then closing the stopcock, the altitude being determined by an observation of the barometer at the moment. In the third tube, a Torricellian vacuum was obtained, the tube being then sealed and drawn off, so as to admit of being broken at a filemark when the air was to be collected; after the specimen had been thus obtained, the aperture was closed by thrusting the neck of the tube into a cap filled with softened wax. "The tubes were within twenty hours after the air had been collected hermetically sealed by myself, and the proportions of oxygen and nitrogen determined with great care by detonation with hydrogen in 'Regnault's Eudiometer.' "The volumes of oxygen found in the air collected at different altitudes are given in the following table: | Altitude | Volume of oxygen | |-------------------|-----------------| | Air collected at King's College | 20·920 | | Tube 2 | 13,460 feet | 20·888 | | Tube 3 | 18,000 feet | 20·747 | | Tube (G 1), Torricellian vacuum | 18,630 feet | 20·888 | "From these observations it would appear that the composition of the atmosphere, as regards the proportion of oxygen and nitrogen, scarcely varies more as we ascend through the first half of that atmosphere (for at an altitude of about 3½ miles one-half of the atmosphere lies beneath us), than it is found to vary at different spots upon the surface: that there is, in fact (as Gay-Lussac had long since announced as the result of his experiments, made at a time when the methods of gaseous analysis were less perfect than at present), no sensible difference in the composition of the atmosphere upon the surface, and at the greatest heights accessible to man. "In quantities of air so limited as those at my disposal, it was not possible to determine accurately the proportion of carbonic acid which they contained. Its presence however was distinctly shown by the formation of a film of carbonate of lead upon a solution of the subacetate which was introduced to a portion of the air confined over mercury. "I have found a form of pipette, a sketch of which I subjoin, very useful for transferring small quantities of gases over mercury. It saves a great deal of fatigue, and I think contributes to precision in the results obtained. Its working is so simple as hardly to require description. It is first completely filled with mercury by closing the lower steel stopcock and opening the upper one, then pouring in mercury by the funnel until the metal escapes by the open end of the long bent tube; the upper stopcock is now closed, the bent tube introduced into the jar containing the gas to be transferred, and the end of the tube is lifted above the level of the metal in the jar of gas; the lower stopcock is then opened, mercury runs out, and gas takes its place; when a sufficient quantity has entered, the end of the tube is depressed beneath the mercury, a little of the metal enters and seals the opening, the lower stopcock is closed, and the pipette with its contents is withdrawn: the bent tube is now introduced beneath the jar which is to receive the gas. The funnel at top is filled with mercury, the upper stopcock opened, and the descending column of mercury expels the gas into the vessel destined to receive it. "I am, my dear Sir, "Yours very truly, "To Colonel Sykes, Chairman of the Kew Committee." "William Allen Miller." **Meteorological Observations during the Ascents at different places.** **Table III.—Places at which Meteorological Observations were taken in connection with the Balloon Ascents of 1852, with the Geographical coordinates, and name of the Observer or Authority.** | Name of Place | Latitude | Longitude | Height above sea level | Authority | |------------------------|----------|-----------|------------------------|--------------------------------| | Armagh | 54° 21' 13" | 6° 38' 52" W. | 209 | Rev. Dr. Robinson, F.R.S. | | Aylesbury | 51° 49' | 0° 49' 15" W. | 284 | Thomas Dell, Esq. | | Bedford | 52° 8' | 0° 28' | 100 | Dr. S. Herbert Barker. | | Cambridge | 52° 12' 52" | 0° 55' 3 E. | 80 | Professor Challis, F.R.S. | | Cardington | 52° 7' | 0° 24' | | S. C. Whitbread, Esq. | | Derby* | 52° 55' | 1° 28' 16" W. | 100? | Mr. Davis, Optician. | | Diss* | 52° 22' | 1° 6' E. | 130 | Thomas E. Amyot, Esq. | | Dublin | 53° 21' | 6° 15' W. | 24½ | Rev. R. V. Dixon, A.M. | | Edinburgh | 55° 27' 23" | 3° 10' 45" W. | 354 | Professor Smyth, F.R.S.E. | | Enfield | 51° 39' | 0° 4' 57" W. | 76½ | Rev. J. M. Heath. | | Grantham | 52° 54' 52" | 0° 39' 0 W. | 190 | J. W. Jeans, Esq. | | Greenwich | 51° 28' 38" | 0° 0' 0 | 159 | The Astronomer Royal. | | Hartwell House | 51° 49' | 0° 51' W. | 250 | Dr. Lee, F.R.S. | | Hartwell Rectory | 51° 48' 36" | 0° 51' W. | 290 | Rev. C. Lowndes, M.A., F.R.A.S. | | Haverhill | 52° 5' | 0° 26' 36" E. | | Wm. W. Boreham, Esq., F.R.A.S. | | Hawarden | 53° 11' 0" | 3° 2' 0 W. | 260 | Dr. T. Moffat, F.R.A.S. | | Highfield House | 52° 57' 30" | 1° 10' W. | 204 | E. J. Lowe, Esq., F.R.A.S. | | Holkham | 52° 57' 10" | 0° 48' E. | 39 | Samuel Shellabear, Esq. | | Kew Observatory | 51° 28' 37" | 0° 15' 45" W. | 40? | Captain Younghusband, R.A., F.R.S. | | Lewisham | 51° 28' | 0° 1' W. | 80 | James Glaisher, Esq., F.R.S. | | Linslade | 51° 55' | 0° 40' W. | 313 | John Osborn, Jun., Esq. | | Marboué | 48° 6' 57" | 1° 20' 3 E. | 361 | M. Le Commandant Deleros. | | Norwich | 52° 37' | 1° 16' E. | 33 | Wm. Brooke, Esq. | | Oxford | 51° 45' 40" | 1° 15' 30" W. | 210 | M. J. Johnson, Esq., F.R.S. | | Rosehill, Oxford | 51° 43' 50" | 1° 14' W. | 270? | John Slatter, Esq. | | Les Rousseaux | 47° 30' 58" | 2° 20' 10" E. | | M. Le Commandant Deleros. | | Royston | 52° 2' 40" | 0° 0' 30 W. | 271 | Hale Wortham, Esq. | | Ryde | 50° 45' | 1° 11' 30 W. | 110 | Benjamin Barrow, Esq. | | Southampton | 50° 54' 34" | 1° 24' 25 W. | 60 | Dr. Drew, F.R.A.S. | | Stone | 51° 47' 57" | 0° 52' 16 W. | 320 | Rev. J. B. Reade, M.A., F.R.S. | | St. Ives* | 52° 20' | 0° 5' W. | | John King Watts, Esq. | | St. John's Wood | 51° 31' | 0° 15' W. | 150 | George Leach, Esq. | | Ventnor* | 50° 36' | 1° 13' W. | 150 | Dr. Martin. | | York | 53° 57' 48" | 1° 4' W. | 50 | John Ford, Esq. | * The barometrical observations at Derby, Diss, St. Ives, and Ventnor have not been corrected for temperature. ### Table IV.—Meteorological Observations, made at Various Places on the days of the Four Balloon Ascents in 1852. | Hour | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | |------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | | | | | | Aylesbury. | | | | Bedford. | | | Cambridge. | | | Cardington. | | | | 9 A.M. | ....... | ....... | ......... | 29·79 | 67·4 | 62·0 | 29·912 | 65·5 | 63·0 | 29·793 | 65·0 | 60·5 | | 2 P.M. | 29·568 | 72·3 | 66·7 | 0·590 | ....... | ......... | 0·498 | ....... | ......... | ....... | ....... | ......... | | 3 | -523 | 73·0 | 68·5 | -642 | ....... | ......... | -813 | 72·0 | 68·6 | -656 | ....... | ......... | | 4 | -515 | 69·8 | 65·7 | -585 | 73·1 | 67·0 | -590 | 71·3 | 68·5 | -660 | 71·7 | 70·0 | | 5 | -502 | 69·3 | 66·0 | -601 | 70·6 | 66·8 | -611 | 70·3 | 68·1 | -658 | 69·9 | 66·0 | | 6 | -485 | 67·0 | 65·7 | -616 | 69·6 | 67·0 | -630 | 70·3 | 67·7 | -656 | 67·8 | 66·0 | | 7 | -477 | 66·0 | 65·0 | -606 | 68·4 | 66·5 | -627 | 67·8 | 66·5 | -622 | 66·8 | 65·0 | | 8 | -487 | 62·0 | 62·0 | -559 | 66·1 | 65·0 | -605 | 67·5 | 66·3 | -631 | -623 | | | Derby. | | | | Dublin. | | | Diss. | | | Enfield. | | | | 2 P.M. | 29·74 | 71·0 | 64·0 | 0·518 | ....... | ......... | 29·85 | 70·0 | 66·0 | 0·593 | ....... | ......... | | 3 | -74 | 72·0 | 65·0 | -538 | 29·679 | 69·2 | 62·7 | -80 | 70·0 | 66·0 | -593 | ....... | ......... | | 4 | -71 | 70·0 | 64·5 | -545 | 68·5 | 62·0 | -486 | 78 | 69·5 | 66·0 | -599 | ....... | ......... | | 5 | -71 | 68·0 | 65·0 | -583 | 67·6 | 61·8 | -490 | 78 | 69·0 | 66·0 | -604 | ....... | ......... | | 6 | -69 | 67·0 | 64·0 | -563 | 68·6 | 69·0 | 60·9 | -472 | 76 | 68·5 | 66·5 | -626 | ....... | ......... | | 7 | -68 | 65·5 | 63·5 | -565 | 68·9 | 63·5 | 59·0 | -456 | 74 | 67·0 | 65·5 | -610 | ....... | ......... | | 8 | -68 | 64·5 | 63·0 | -561 | 70·9 | 62·5 | 58·9 | -464 | 73 | 65·0 | 64·0 | -586 | ....... | ......... | | Edinburgh. | | | | Haverhill. | | | Hawerden, Chester. | | | Highfield House. | | | | 9 A.M. | ....... | ....... | ......... | ....... | ....... | ......... | ....... | ....... | ......... | 29·722 | 69·2 | 63·3 | | 2 P.M. | 29·279 | 67·7 | | ....... | ....... | ......... | ....... | ....... | ......... | ....... | ....... | ......... | | 3 | -264 | 67·5 | | ....... | ....... | ......... | ....... | ....... | ......... | ....... | ....... | ......... | | 4 | -282 | 66·2 | | ....... | ....... | ......... | ....... | ....... | ......... | ....... | ....... | ......... | | 5 | -674 | 69·5 | 66·8 | -588 | ....... | ......... | ....... | ....... | ......... | ....... | ....... | ......... | | 6 | -663 | 68·0 | 66·5 | -631 | ....... | ......... | ....... | ....... | ......... | ....... | ....... | ......... | | 7 | -629 | 66·2 | 64·8 | -597 | ....... | ......... | ....... | ....... | ......... | ....... | ....... | ......... | | Holkham. | | | | Linslade. | | | Norwich. | | | Oxford. | | | | 9 A.M. | 29·888 | 66·5 | 62·4 | 0·520 | 29·595 | 64·0 | 59·3 | 0·558 | 29·906 | 68·0 | 64·0 | 0·552 | 29·630 | 72·1 | 66·4 | | 2 P.M. | -525 | 69·3 | 63·3 | -516 | ....... | ......... | ....... | ....... | ......... | ....... | ....... | ......... | | 3 | -796 | 74·4 | 67·2 | -582 | 505 | 71·3 | 64·2 | -521 | 786 | 73·0 | 68·0 | -625 | -615 | 70·4 | 66·0 | | 4 | -785 | 72·3 | 66·4 | -581 | ....... | ......... | ....... | ....... | ......... | ....... | ....... | ......... | | 5 | -784 | 72·2 | 67·0 | -601 | -457 | 68·5 | 64·9 | -575 | 756 | 72·0 | 68·0 | -636 | -577 | 67·6 | 65·1 | | 6 | -763 | 68·8 | 65·2 | -581 | -454 | 67·4 | 65·1 | -593 | 748 | 70·0 | 67·0 | -625 | -507 | 66·0 | 64·8 | | 7 | -756 | 67·2 | 64·7 | -583 | ....... | ......... | ....... | ....... | ......... | ....... | ....... | ......... | | 8 | -735 | 66·3 | 64·0 | -571 | -420 | 63·9 | 62·3 | -546 | 709 | 65·0 | 64·5 | -601 | -512 | 65·1 | 64·7 | | Roselhill, Oxford. | | | | Ryde. | | | Southampton. | | | St. Ives. | | | | 9 A.M. | 29·639 | 65·0 | 61·0 | 0·497 | 29·850 | 63·8 | 61·9 | 0·536 | 29·812 | 66·1 | 63·0 | 0·544 | 29·70 | 73·0 | | 2 P.M. | -748 | 65·9 | 65·7 | -629 | -729 | 71·0 | 67·0 | -615 | -69 | 72·0 | | 3 | -554 | 68·6 | 64·7 | -568 | -731 | 66·8 | 66·2 | -635 | -711 | 67·7 | 66·0 | -619 | -68 | 72·0 | | 4 | -507 | 66·5 | 64·5 | -585 | -667 | 65·8 | 64·2 | -583 | -674 | 67·9 | 65·6 | -603 | -68 | 72·0 | | 5 | -529 | 65·0 | 64·8 | -611 | -667 | 65·8 | 63·7 | -568 | -656 | 67·0 | 66·0 | -627 | -68 | 72·0 | | 6 | -443 | 65·0 | 64·6 | -605 | -639 | 64·9 | 64·2 | -593 | -626 | 66·0 | 65·0 | -606 | -65 | 70·0 | | 7 | ....... | ....... | ......... | ....... | -622 | 64·8 | 63·7 | -579 | -624 | 64·0 | 62·9 | -574 | -65 | 68·0 | | 8 | ....... | ....... | ......... | ....... | -623 | 64·0 | 63·5 | -581 | -867 | 63·5 | 62·0 | -542 | -58 | 67·0 | ## OBSERVATIONS IN FOUR BALLOON ASCENTS. ### TABLE IV. (Continued.) | Hour | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | |------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | | | | | | St. John's Wood. | York. | | | | | | | | | | | | | 9 A.M. | 29·785 | 62·8 | 60·3 | 0·500 | 29·721 | 66·0 | 63·0 | 0·545 | | | | | | | | 2 P.M. | | | | | | | | | | | | | | 3 | ·663 | 69·8 | 66·3 | ·605 | ·734 | 71·0 | 64·5 | ·535 | | | | | | | | 4 | ·647 | 69·5 | 66·5 | ·615 | ·710 | 71·0 | 64·0 | ·519 | | | | | | | | 5 | ·608 | 68·8 | 65·8 | ·600 | ·701 | 69·0 | 64·0 | ·542 | | | | | | | | 6 | ·596 | 68·6 | 66·2 | ·615 | ·701 | 69·0 | 64·0 | ·542 | | | | | | | | 7 | ·552 | 68·8 | 66·4 | ·620 | ·713 | 68·0 | 63·5 | ·537 | | | | | | | | 8 | ·580 | 65·0 | 64·0 | ·586 | ·707 | 66·0 | 64·0 | ·575 | | | | | | | **Observations on August 17, 1852.** | Hour | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | |------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | | | | | | Armagh. | Grantham. | Greenwich. | Lewisham. | | | | | | | | | | | 9 A.M. | 29·297 | 65·5 | 62·6 | 0·538 | 29·688 | 66·4 | 61·4 | 0·493 | 29·804 | 64·0 | 58·1 | 0·426 | 29·762 | 74·9 | 69·2 | 0·645 | | 3 P.M. | | | | | | | | | | | | | | | | | 3½ | | | | | | | | | | | | | | | | | 4 | | | | | | | | | | | | | | | | | 4½ | | | | | | | | | | | | | | | | | 5 | ·437 | 64·2 | 58·6 | ·437 | ·571 | 67·5 | 63·5 | ·544 | ·636 | 70·6 | 65·0 | ·555 | ·714 | 70·7 | 67·5 | ·635 | | 5½ | ·440 | 64·6 | 58·8 | ·438 | ·579 | 67·4 | 63·5 | ·544 | ·623 | 69·8 | 65·0 | ·564 | ·686 | 70·0 | 67·1 | ·629 | | 6 | ·449 | 65·0 | 59·1 | ·442 | ·584 | 66·9 | 63·1 | ·538 | ·619 | 69·1 | 65·1 | ·575 | ·688 | 69·1 | 67·0 | ·636 | | 6½ | ·446 | 64·5 | 59·1 | ·442 | ·561 | 66·2 | 62·8 | ·536 | ·602 | 68·6 | 65·4 | ·590 | ·648 | 68·4 | 67·6 | ·652 | | 7 | ·446 | 64·1 | 58·6 | ·438 | ·551 | 65·9 | 62·6 | ·533 | ·607 | 61·4 | 60·5 | ·521 | ·656 | 64·0 | 63·7 | ·588 | | 7½ | ·464 | 61·4 | 57·2 | ·429 | ·546 | 65·6 | 62·6 | ·537 | ·593 | 62·5 | 61·0 | ·524 | ·672 | 63·2 | 62·8 | ·570 | | 8 | ·451 | 59·6 | 57·0 | ·444 | ·548 | 64·8 | 63·0 | ·558 | ·593 | 63·5 | 61·6 | ·530 | | | | | | 8½ | | | | | | | | | | | | | | | | | 9 | | | | | | | | | | | | | | | | **Observations on August 26, 1852.** | Hour | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | |------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | | | | | | Aylesbury. | Bedford. | Cambridge. | Derby. | | | | | | | | | | | 9 A.M. | | | | | | | | | | | | | | 2 P.M. | | | | | | | | | | | | | | 3 | ·722 | 73·5 | 66·3 | ·564 | ·043 | 72·1 | 65·8 | ·562 | ·020 | 68·4 | 64·9 | ·576 | ·29·97 | 68·0 | 62·0 | 0·492 | | 4 | ·727 | 70·6 | 65·0 | ·555 | ·062 | 70·0 | 65·0 | ·561 | ·017 | 67·8 | 64·8 | ·579 | ·98 | 68·0 | 63·0 | ·522 | | 5 | ·734 | 69·9 | 65·4 | ·575 | ·070 | 69·4 | 64·5 | ·552 | ·018 | 67·7 | 64·1 | ·559 | ·98 | 67·0 | 62·0 | ·503 | | 6 | ·744 | 66·0 | 63·3 | ·553 | ·070 | 66·5 | 63·0 | ·539 | ·031 | 66·4 | 63·0 | ·540 | ·29·98 | 65·0 | 61·0 | ·496 | | 7 | ·759 | 60·7 | 59·7 | ·507 | ·079 | 64·0 | 61·5 | ·522 | ·056 | 63·2 | 60·9 | ·513 | ·30·00 | 62·0 | 59·0 | ·472 | | 8 | ·775 | 58·7 | 58·2 | ·486 | ·079 | 61·2 | 60·0 | ·510 | ·065 | 61·0 | 58·8 | ·477 | | | | | **Observations on August 26, 1852.** | Hour | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | |------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | | | | | | Diss. | Edinburgh. | Enfield. | Holkham. | | | | | | | | | | | 9 A.M. | | | | | | | | | | | | | | 2 P.M. | | | | | | | | | | | | | | 3 | ·97 | 65·5 | 61·0 | ·491 | | | | | | | | | | | 4 | ·97 | 65·0 | 61·0 | ·496 | | | | | | | | | | | 5 | ·98 | 63·5 | 61·5 | ·528 | 29·634 | 66·7 | | | | | | | | | 6 | ·98 | 62·5 | 59·3 | ·480 | | | | | | | | | | | 7 | ·99 | 59·5 | 57·0 | ·445 | | | | | | | | | | | 8 | | | | | | | | | | | | | **Observations on August 26, 1852.** | Hour | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | |------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | | | | | | Norwich. | Oxford. | Royston. | Southampton. | | | | | | | | | | | 9 A.M. | | | | | | | | | | | | | | 2 P.M. | | | | | | | | | | | | | | 3 | ·040 | 66·0 | 60·0 | ·456 | ·822 | 71·0 | 64·6 | ·538 | ·29·784 | 70·1 | 63·3 | ·507 | ·29·911 | 64·1 | 62·4 | ·547 | | 4 | ·044 | 65·5 | 60·0 | ·461 | ·832 | 68·4 | 64·0 | ·548 | ·799 | 66·8 | 62·2 | ·512 | ·925 | 69·0 | 66·5 | ·620 | | 5 | ·046 | 65·0 | 60·0 | ·467 | ·830 | 67·0 | 63·8 | ·557 | ·798 | 63·7 | 60·0 | ·482 | ·929 | 65·0 | 63·7 | ·576 | | 6 | ·052 | 62·0 | 59·0 | ·472 | ·848 | 65·3 | 62·2 | ·528 | ·822 | 60·5 | 58·5 | ·477 | | | | | | 7 | ·058 | 59·0 | 57·5 | ·464 | ·857 | 63·0 | 61·0 | ·519 | ·827 | 58·0 | 56·8 | ·457 | | | | | | 8 | ·066 | 55·0 | 54·5 | ·429 | | | | | | | | | | | | | | MDCCCLIIII. ### Table IV (Continued) | Hour | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | |------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | | | | | | | in. | in. | | in. | in. | | in. | in. | | in. | in. | | | | Stone. | St. Ives. | St. John's Wood. | Grantham. | Greenwich. | Kew. | Lewisham. | | 9 A.M. | 29-637 | 67-4 | 64-0 | 0-559 | ... | ... | ... | 29-862 | 62-8 | 61-3 | 0-529 | | 2 P.M. | -646 | 72-6 | 65-6 | .551 | 29-85 | 72-0 | ... | ... | ... | ... | ... | | 3 | -648 | 68-9 | 64-0 | .543 | 85 | 71-0 | ... | 866 | 68-5 | 64-2 | .553 | | 4 | -646 | 68-9 | 64-5 | .558 | 85 | 69-0 | ... | 874 | 67-8 | 63-8 | .548 | | 5 | -656 | 68-7 | 63-5 | .529 | 86 | 69-0 | ... | 879 | 66-8 | 63-8 | .560 | | 6 | -664 | 66-6 | 62-9 | .535 | 87 | 68-0 | ... | 888 | 64-8 | 62-8 | .552 | | 7 | -689 | 63-0 | 60-3 | .498 | 89 | 64-0 | ... | 911 | 62-8 | 60-4 | .503 | | 8 | -694 | 60-9 | 58-8 | .479 | 90 | 61-0 | ... | 920 | 61-8 | 59-8 | .497 | **Observations on August 26, 1852.** | Hour | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | |------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | | | | | | | in. | in. | | in. | in. | | in. | in. | | in. | in. | | | | Bedford. | Enfield. | Hartwell House. | Linslade. | Norwich. | Oxford. | Rosehill, Oxford. | | 9 A.M. | 29-94 | 46-6 | 46-0 | 0-318 | 29-984 | 46-5 | 45-9 | 0-317 | 29-810 | 49-3 | 47-8 | 0-329 | 29-695 | 47-8 | 47-8 | 0-346 | | 1 P.M. | -88 | 56-6 | 53-5 | .385 | -917 | 52-0 | 50-2 | .356 | -766 | 56-8 | 51-0 | .321 | -766 | 55-8 | 51-0 | .332 | | 2 | -86 | 57-0 | 54-0 | .394 | -906 | 52-0 | 50-9 | .373 | -750 | 55-8 | 51-2 | .343 | -742 | 54-0 | 51-0 | .352 | | 3 | -85 | 56-4 | 53-0 | .375 | -891 | 52-0 | 51-5 | .387 | -750 | 55-8 | 51-2 | .343 | -742 | 54-0 | 51-0 | .352 | | 4 | -85 | 55-0 | 51-8 | .361 | -871 | 52-1 | 51-8 | .394 | -750 | 55-8 | 51-2 | .343 | -742 | 54-0 | 51-0 | .352 | | 5 | -85 | 54-0 | 51-7 | .369 | -871 | 52-0 | 52-0 | .400 | -750 | 55-8 | 51-2 | .343 | -742 | 54-0 | 51-0 | .352 | | 6 | -87 | 54-0 | 51-7 | .369 | -886 | 51-5 | 51-0 | .380 | -754 | 54-9 | 51-9 | .364 | -734 | 54-6 | 53-0 | .395 | | 7 | -87 | 54-1 | 52-0 | .376 | -874 | 54-1 | 52-0 | .376 | -734 | 54-6 | 53-0 | .395 | -734 | 54-6 | 53-0 | .395 | **Observations on October 21, 1852.** | Hour | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | |------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | | | | | | | in. | in. | | in. | in. | | in. | in. | | in. | in. | | | | Ryde. | Stone. | St. John's Wood. | Ventnor. | | 9 A.M. | 29-933 | 53-1 | 52-0 | 0-388 | 29-649 | 48-3 | 47-8 | 0-340 | 29-892 | 46-5 | 45-6 | 0-313 | | 1 P.M. | -897 | 59-8 | 55-5 | .402 | -617 | 54-6 | 52-4 | .380 | -827 | 56-0 | 52-5 | .367 | -827 | 56-0 | 52-5 | .367 | | 2 | -889 | 59-0 | 55-0 | .397 | -597 | 56-3 | 53-5 | .389 | -815 | 55-8 | 53-8 | .390 | -802 | 60-0 | 57-0 | .440 | | 3 | -889 | 59-0 | 55-0 | .397 | -586 | 54-4 | 51-6 | .362 | -810 | 57-5 | 53-8 | .386 | -874 | 60-0 | 57-0 | .440 | | 4 | -874 | 53-7 | 51-6 | .370 | -795 | 54-5 | 51-9 | .369 | -872 | 60-0 | 57-0 | .440 | -872 | 60-0 | 57-0 | .440 | | 5 | -871 | 53-0 | 51-3 | .371 | -795 | 54-9 | 52-8 | .387 | -872 | 60-0 | 57-0 | .440 | -872 | 60-0 | 57-0 | .440 | | 6 | -887 | 56-0 | 54-8 | .426 | -578 | 53-4 | 51-5 | .372 | -804 | 54-8 | 52-8 | .389 | -874 | 60-0 | 57-0 | .440 | | 7 | -662 | 52-7 | 51-5 | .379 | -792 | 54-0 | 52-5 | .389 | -874 | 60-0 | 57-0 | .440 | -874 | 60-0 | 57-0 | .440 | | 8 | -554 | 52-7 | 51-9 | .389 | -783 | 53-0 | 52-0 | .389 | -874 | 60-0 | 57-0 | .440 | -874 | 60-0 | 57-0 | .440 | | 9 | -550 | 52-7 | 51-9 | .389 | -783 | 53-0 | 52-0 | .389 | -874 | 60-0 | 57-0 | .440 | -874 | 60-0 | 57-0 | .440 | ## Observations in Four Balloon Ascents ### Table IV (Continued) | Hour | Barom. | Therm. | Tension of Vapour | |------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | #### Grantham | Hour | Barom. | Therm. | Tension of Vapour | |------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | #### Greenwich | Hour | Barom. | Therm. | Tension of Vapour | |------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | #### Lewisham | Hour | Barom. | Therm. | Tension of Vapour | |------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | #### Bedford | Hour | Barom. | Therm. | Tension of Vapour | |------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | #### Cambridge | Hour | Barom. | Therm. | Tension of Vapour | |------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | #### Diss. | Hour | Barom. | Therm. | Tension of Vapour | |------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | #### Hartwell House | Hour | Barom. | Therm. | Tension of Vapour | |------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | #### Enfield | Hour | Barom. | Therm. | Tension of Vapour | |------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | #### Grantham | Hour | Barom. | Therm. | Tension of Vapour | |------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | #### Greenwich | Hour | Barom. | Therm. | Tension of Vapour | |------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | #### Lewisham | Hour | Barom. | Therm. | Tension of Vapour | |------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | #### Stone | Hour | Barom. | Therm. | Tension of Vapour | |------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | #### St. Ives | Hour | Barom. | Therm. | Tension of Vapour | |------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | #### Norwich | Hour | Barom. | Therm. | Tension of Vapour | |------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | #### St. John's Wood | Hour | Barom. | Therm. | Tension of Vapour | |------|--------|--------|-------------------| | | | Dry. | Wet. | | | | | | TABLE IV. (Continued.) | Hour | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | Barom. | Therm. | Tension of Vapour. | |------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------|--------|--------|-------------------| | | in. | Dry. | Wet. | in. | Dry. | Wet. | in. | Dry. | Wet. | in. | Dry. | Wet. | | Les Rousseaux, Aug. 17. | Les Rousseaux, Aug. 26. | Marboué, Oct. 21. | Marboué, Nov. 10. | | 7 A.M. | 29·475 | 67·1 | 62·0 | 0·502 | 29·443 | 63·1 | 59·0 | 0·460 | 29·752 | 34·9 | 32·7 | 0·179 | 29·719 | 43·0 | 41·2 | 0·255 | | 9 | ·456 | 69·1 | 63·1 | ·513 | ·445 | 72·0 | 61·3 | ·427 | ·752 | 52·0 | 47·1 | ·283 | ·703 | 49·3 | 46·4 | ·297 | | Noon | ·395 | 76·7 | 66·4 | ·534 | ·449 | 78·8 | 66·9 | ·525 | ·691 | 60·1 | 53·2 | ·338 | ·668 | 57·6 | 52·7 | ·354 | | 3 P.M.| ·296 | 80·8 | 68·2 | ·546 | ·454 | 78·3 | 67·6 | ·553 | ·667 | 59·2 | 54·1 | ·371 | ·650 | 56·3 | 50·7 | ·319 | | 9 | ·297 | 70·5 | 67·3 | ·630 | ·494 | 67·8 | 63·0 | ·524 | ·635 | 49·5 | 46·8 | ·304 | ·628 | 44·6 | 41·9 | ·252 | DESCRIPTION OF THE PLATES. PLATE XIX. XX. XXI. and XXII. The results for each ascent of the observations of temperature, tension of vapour, and relative humidity are projected in these Plates. For the most part each individual observation is given, except when they were very numerous and occurring at too close intervals of height to be easily represented. In such cases groups have been taken, but no group ever contains more observations than were recorded within 200 feet. The ordinates represent the height above the level of the sea, one division being equivalent to 200 feet; the abscissæ representing the temperature of the air, the tension of vapour, or the relative humidity. The scale employed for the temperature is one division to 2° Fahr.; for the tension of vapour, ten divisions to 0·2 inch of pressure of mercury; and for the relative humidity, twenty divisions to the whole range 0—100. The straight lines drawn through the curves of temperature are deduced from the results of equation (1.) for the upper and lower divisions in each series (see p. 25). The points ⊙ in the curves of tension of vapour are from the indications of Regnault’s hygrometer. In the divisions occupied by the relative humidity the strong vertical lines correspond to the heights at which clouds existed in the air, dotted lines being drawn when the cloud was only partial.