Meteorological Observations Made on Board Her Majesty's (Hired) Bark Pagoda, from January 10 to June 20, 1845, between -20 degrees and -68 degrees Latitude, and 0 degrees and 120 degrees East Longitude

XIX. Meteorological Observations made on Board Her Majesty's (hired) Bark Pagoda, from January 10 to June 20, 1845, between −20° and −68° Latitude, and 0° and 120° East Longitude. By Lieut. Henry Clerk, Royal Artillery. Communicated by Lieut.-Colonel Sabine, R.A., For. Sec. R.S., &c. Received April 21, 1846,—Read May 28, 1846. As much interest has been taken of late in the state of the barometer in high southern latitudes, the Expedition sent last year from the Cape of Good Hope to complete the magnetical observations made by Sir James C. Ross in those latitudes, was supplied with a barometer and other meteorological instruments, and directed to make meteorological as well as magnetical observations. I have now the honour of laying before the Royal Society the observations made during that Expedition. They were taken daily at the hours of 3 and 9 A.M., 3 and 9 P.M., noon, and midnight, by the officers of the ship during their respective watches. Nothing could exceed the zeal with which the officers entered into all the objects of the Expedition, and the attention and care they took in the observations they had to make. The following are the instruments with which the Expedition was furnished: One marine barometer, Three thermometers, One Daniell's hygrometer, Ether in metal bottles. by J. Newman, London. The barometer was of the usual construction, the case being of wood and the scale of ivory, read off by a vernier to '01 of an inch; the mercury was contained in a leathern bag. It was compared with the standard barometer at the Magnetic Observatory, Cape of Good Hope, both before and after the Expedition; and also with the Royal Society's barometer on its return to England. The following are the comparisons: Cape of Good Hope.—January 1845. | Standard Barometer | Thermometer | Marine Barometer | Thermometer | Marine below standard | |--------------------|-------------|------------------|-------------|----------------------| | inches. | | inches. | | | | 29·863 | 67·9 | 29·753 | 67·3 | | | 29·896 | 68·1 | 29·785 | 67·5 | | | 29·949 | 69·4 | 29·834 | 69·1 | | | 30·001 | 70·4 | 29·884 | 70·4 | | | 30·067 | 69·0 | 29·948 | 68·5 | | | 30·090 | 69·4 | 29·975 | 68·8 | | inch. '115 Cape of Good Hope.—June 1845. | Standard | Marine | Marine below standard. | |----------|--------|-----------------------| | Barometer. | Thermometer. | Barometer. | Thermometer. | | inches. | inches. | inches. | | 30-302 | 55·7 | 30-125 | 55·7 | | 30-195 | 58·9 | 30-000 | 58·6 | | 30-096 | 59·3 | 29-933 | 59·1 | | 30-515 | 52·4 | 30-370 | 52·7 | | 30-097 | 54·2 | 29-935 | 54·3 | | 30-394 | 53·8 | 30-225 | 53·9 | At the Royal Society's Rooms, London.—March 1846. | Standard | Marine | Marine below standard. | |----------|--------|-----------------------| | Barometer. | Thermometer. | Barometer. | Thermometer. | | inches. | inches. | inches. | | 29·548 | 42·5 | 29·390 | 42·5 | | 29·430 | 29·280 | 29·450 | 1·49 | From these comparisons it would appear that a change of 0·05 may have taken place in the barometer during the Expedition: as the time is not known when the change took place, the mean of the three comparisons, viz. +1·144 has been applied to all the observations. They have also been corrected for the effect of temperature on the mercurial column, the corrections being taken from the Table given in the Royal Society's Instructions for Magnetical and Meteorological Observatories, p. 82. The daily means thus corrected are given in the Abstract in Table I. Table II. contains the means of every seven successive days; these means have had an additional correction applied to them, for the variation in the length of the column of mercury occasioned by the variation of gravity in different latitudes. The correction in lat. —2° amounts to —0·059 The correction in lat. —45 amounts to —0·000 The correction in lat. —70 amounts to +0·059 and proportionally for intermediate latitudes. Table III. contains the general results arranged according to latitude. This has been done by grouping together, without reference to date, the weekly means belonging to nearly similar latitudes. The number of observations, of which each general result is the mean, is given in the last column of the Table. In order to resolve the heights of the barometer into the two constituents of aqueous and gaseous pressure, one of Daniell's hygrometers was observed at the hours of 9 A.M. and 3 P.M., by Assistant-Surgeon W. Dixon, M.D., attached to the Expedition. The tension of vapour obtained by these observations is taken from the Table in the Royal Society's Instructions (page 89). This being deducted from the height of the barometer in Tables II. and III., leaves the pressure of the dry air. The thermometers, employed for observing the temperature of the air and of the surface of the sea, were frequently tested by immersing them in melting snow, and the necessary corrections have been applied. The thermometers were found to have very little index error. The temperature of the surface of the sea was obtained by drawing up water in a small canvas bucket and immersing a thermometer immediately into it. The directions of the wind are the true ones, i.e., the observed compass direction corrected for the declination. The force of the wind and the state of weather were recorded according to the system drawn up by Captain Beaufort for the use of the Royal Navy;—frequent attempts were made to observe the force of the wind by means of one of Lind's gauges, but owing to the rolling motion of the ship it was found impossible. The observations in the Pagoda show a lower barometer within the Tropics than a little beyond them; the mercury rising from latitude $-20^\circ$ to about $-35^\circ$, where it stood at $30^\circ15'$. From latitude $-35^\circ$ to $-56^\circ$ the barometer fell rapidly, the difference being $1.054$ inch. The descent of the mercury with the increase of latitude did not appear to extend beyond $-56^\circ$, as in the forty days during which the Pagoda was between $-60^\circ$ and $-67^\circ5$, the mean height of the barometer scarcely differed from the mean corresponding to $-56^\circ21'$. The gaseous pressure presents similar features, rising from $-20^\circ$ to $-35^\circ$, thence descending to $-56^\circ$, and remaining nearly constant from $-56^\circ$ to $-67^\circ$. The difference between lat. $-35^\circ$ and lat. $-56^\circ$ amounts in this case to $0.78$ inch. No influence of longitude on the barometer is deducible from these observations, extending from $0^\circ$ to $120^\circ$ East. For the purpose of comparing these results with the inferences which have been derived from previous observations, I have added an abstract of the conclusions drawn from the observations discussed in Dr. Adolph Erman's work*, which has been communicated to me by Lieut.-Colonel Sabine. "From a parallel very near the equator, the pressure of the atmosphere, measured by the barometer corrected for gravity, increases both northward and southward to a little beyond the outer limit of the trade winds; beyond this limit the pressure decreases, at first slowly, but much more rapidly after passing the 50th parallel. The maximum of pressure occurs at about $35^\circ$ in each hemisphere. The decrease from the maximum in the direction of the Pole has been found in the southern hemisphere to continue as far as the parallel of Cape Horn ($-55^\circ5$), where the low pressure corresponds with that observed in the northern hemisphere at Kamtchatka and Sitka, which are nearly in the same latitude. "The dry air has also a minimum zone within the inner limits of the trades; the increase from thence in both directions is more rapid and considerable than that of the pressure of the gaseous and aqueous atmospheres united, and the gaseous maximum in both hemispheres is obtained in a higher latitude (about $45^\circ$). The pressure * Ueber Meteorologische Beobachtungen bei einer Seereise um die Erde. of the dry air at its maximum at $45^\circ$ exceeds the equatorial gaseous pressure by about $0.47$ inch; the pressure of the whole atmosphere at its maximum in $35^\circ$ is not more than $0.18$ above the equatorial pressure. "The following Table contains the approximate mean annual pressures of the atmosphere corresponding to different latitudes, as given by Dr. Erman:—1. Of the barometer; 2, of the vapour; and 3, of the dry air. The Table is formed from observations in both hemispheres, and in both the Pacific and Atlantic Oceans; it also unites observations made in different seasons, with a single exception. | Latitude | Barometer | Tension of the vapour | Pressure of the dry air | Remarks | |----------|-----------|-----------------------|-------------------------|---------| | | inches | in. | in. | | | 0 | 29.98 | 0.77 | 29.21 | | | 5 | 30.00 | 0.77 | 29.23 | | | 10 | 30.03 | 0.75 | 29.28 | | | 15 | 30.07 | 0.70 | 29.37 | | | 20 | 30.11 | 0.65 | 29.46 | | | 25 | 30.14 | 0.61 | 29.53 | | | 30 | 30.15 | 0.55 | 29.60 | | | 35 | 30.16 | 0.50 | 29.66 | | | 40 | 30.12 | 0.44 | 29.68 | | | 45 | 30.03 | 0.35 | 29.68 | | | 50 | 29.90 | 0.26 | 29.64 | Winter only. | | 55 | 29.64 | 0.22 | 29.42 | | "The summer pressures of the dry air are less than the winter ones, except at the equator; the contrary is the case with the vapour." On comparing Dr. Erman's conclusions with those drawn from the observations in the Pagoda, it appears that they agree in placing the maximum barometric pressure in lat. $35^\circ$, the pressure diminishing thence rapidly to $56^\circ$, where the Pagoda's observations show it to become nearly stationary; but they differ as to the place of the maximum pressure of the dry air, that being in lat. $40^\circ$ or $45^\circ$ by Dr. Erman's observations, and in lat. $35^\circ$ by those of the Pagoda. It is possible however that a longer series of observations would have made the present ones agree more closely in this respect also with those of Dr. Erman, his means being taken from observations made in different seasons, and in various longitudes in both hemispheres. Taking from Dr. Erman's table $29.21$ as the mean pressure of the dry air at the equator, the observations in the Pagoda show a difference of gaseous pressure between the equator and the high latitudes ($-56^\circ$ to $-67^\circ.5$) of the southern hemisphere amounting to $0.28$ inch; the observations in the Pagoda were however exclusively in the summer months, when the pressures are generally less than on the mean of the whole year. Owing to the increase in the elastic force of the aqueous vapour in the warmer regions of the globe, the difference of barometric pressure between the equator and the high latitudes (taking the data from Dr. Erman's table on the one hand, and from the observations in the Pagoda on the other) amounts to $0.89$ inch. As the facts shown by these observations are curious, and must be interesting to meteorologists, it is hoped that the Royal Society will not consider this paper unworthy of their acceptance. ### Table I.—Daily Abstract of Meteorological Observations made on board Her Majesty's (hired) Bark "Pagoda," from the 10th of January to the 20th of June 1845, between −20° and −68° latitude and 0° and 120° east longitude. | Date | Position | Temperature | Hygrometer | Wind | Remarks | |------|----------|-------------|------------|------|---------| | | Lat. | Long. | Corrected barom. | Dew-point | Elasticity of vapour | Direction | Force | | | Jan. | | | | | | | | | | 1845 | 10. | −34 46' | 9 46 | 20-216 | 65 | 59 | .497 | s. by e. | 4 | Passing clouds. | | | 11. | 35 29' | 15 09 | 20-154 | 66 | 66 | .462 | s. by w. | 2 | Passing clouds. | | | 12. | 35 17' | 14 00 | 20-173 | 65 | 67 | .556 | s. by w. | 2 | Passing clouds. | | | 13. | 35 18' | 13 25 | 20-153 | 66 | 67 | .597 | w. by n. | 2 | Cloudy. | | | 14. | 37 29' | 13 24 | 20-104 | 60 | 62 | .381 | s.w. by w. | 4 | Cloudy and misty. | | | 15. | 38 37' | 14 29 | 20-240 | 56 | 57 | .359 | s.w. by s. | 3 | Overcast and squally; strong breezes. | | | 16. | 39 07' | 14 40 | 20-203 | 59 | 60 | .392 | w. by n. | 1 | Passing clouds. | | | 17. | 40 34' | 14 23 | 29-967 | 60 | 60 | .424 | w. by s. | 4 | Passing clouds and misty. | | | 18. | 43 00' | 13 00 | 29-693 | 56 | 57 | .336 | w. by n. | 7 | Overcast; threatening and squally. | | | 19. | 44 58' | 13 19 | 29-714 | 43 | 44 | .220 | w. | 7 | Overcast and squally; passing showers. | | | 20. | 46 34' | 13 33 | 29-362 | 41 | 42 | .208 | N.W.N.W. | 7 | Overcast; squally; heavy rain. | | | 21. | 47 45' | 12 25 | 29-728 | 39 | 40 | .178 | E.S.E. | 3 | Overcast; squally; passing snow. | | | 22. | 48 45' | 10 47 | 29-381 | 40 | 41 | .236 | N.N.W. | 4 | Overcast; squally. | | | 23. | 50 40' | 10 23 | 29-299 | 39 | 39 | .227 | W. | 3 | Overcast and misty; drizzling rain. | | | 24. | 51 47' | 9 34 | 29-258 | 38 | 37 | .214 | W.N.W. | 1 | Cloudy and snow. | | | 25. | 53 06' | 7 49 | 29-309 | 36 | 35 | .163 | W.S.W. | 4 | Overcast; squally and snow; icebergs and stream-ice. | | | 26. | 53 55' | 6 06 | 29-590 | 35 | 35 | .159 | S.S.E. | 3 | Cloudy; numerous icebergs. | | | 27. | 53 13' | 5 57 | 29-743 | 34 | 34 | .163 | S.W. by W. | 4 | Cloudy; numerous icebergs. | | | 28. | 57 33' | 4 08 | 29-164 | 33 | 34 | Not observed. | N.N.W. | 8 | Overcast; squally and snow. | | | 29. | 59 02' | 4 19 | 28-928 | 33 | 32 | .159 | Westerly. | 8 | Cloudy; passing snow; numerous icebergs. | | | 30. | 60 43' | 4 00 | 28-770 | 32 | 32 | .162 | W.S.W. | 6 | Overcast and squally; pack ice southward to south-west. | | | 31. | 61 10' | 9 07 | 28-769 | 34 | 33 | .182 | S.westerly. | 5 | Overcast and snow; misty. | | Feb. | 1. | 62 02' | 12 49 | 28-575 | 34 | 33 | .193 | Southerly. | 7 | Cloudy; squally and passing snow. | | | 2. | 61 54' | 16 27 | 28-953 | 34 | 34 | .199 | Southerly. | 6 | Cloudy and squally; no ice in sight. | | | 3. | 61 59' | 14 19 | 29-281 | 34 | 34 | .186 | Southerly. | 2 | Passing clouds. | | | 4. | 62 00' | 20 36 | 29-243 | 33 | 33 | .177 | N.E. by E. | 3 | Overcast; passing snow. | | | 5. | 62 19' | 21 15 | 29-994 | 32 | 32 | .161 | E. by N. | 1 | Overcast; broken ice in streams. | | | 6. | 62 35' | 24 00 | 29-375 | 32 | 32 | .172 | N.E. by N. | 1 | Passing clouds; very clear. | | | 7. | 62 39' | 28 40 | 29-653 | 32 | 32 | .169 | N. by E. | 4 | Passing clouds; very clear. | | | 8. | 62 35' | 30 45 | 29-711 | 30 | 29 | .144 | S.E. | 2 | Passing clouds; misty. | | | 9. | 62 36' | 36 50 | 29-271 | 28 | 29 | .141 | N.E. by W. | 4 | Passing clouds. | | | 10. | 67 03' | 39 51 | 29-271 | 31 | 31 | .136 | E. by N. | 2 | Cloudy; no ice in sight. | | | 11. | 67 38' | 39 41 | 29-173 | 30 | 30 | .139 | Easterly. | 1 | Passing clouds and snow; pack ice in sight. | | | 12. | 66 40' | 39 24 | 29-221 | 29 | 29 | .134 | E. by S. | 2 | Overcast; passing snow. | | | 13. | 67 25' | 40 14 | 28-912 | 31 | 31 | .133 | N.E. by E. | 6 | Cloudy and snow squalls. | | | 14. | 66 25' | 40 01 | 28-694 | 32 | 32 | .159 | E. by N. | 9 | Cloudy and snow squalls; strong gale. | | | 15. | 65 38' | 38 52 | 28-682 | 32 | 32 | .163 | E. by N. | 10 | Cloudy and snow squalls; strong gale. | | | 16. | 64 52' | 38 37 | 28-761 | 34 | 33 | .172 | E. by N. | 4 | Cloudy and fog. | | | 17. | 64 52' | 40 12 | 28-937 | 34 | 34 | .172 | N. ½ E. | 2 | Cloudy; snow. | | | 18. | 64 22' | 40 29 | 28-674 | 33 | 33 | .153 | N.E. ¼ E. | 9 to 11 | Overcast; heavy gale; incessant snow. | | | 19. | 64 00' | 41 06 | 28-606 | 33 | 34 | .168 | N.W. by N. | 4 | Overcast. | | | 20. | 63 19' | 45 45 | 29-104 | 33 | 33 | .159 | N.W. by W. | 5 | Passing clouds and misty. | | | 21. | 63 36' | 46 48 | 28-814 | 33 | 33 | .146 | N. by E. | 0 | Passing clouds and snow. | | | 22. | 63 43' | 49 29 | 28-707 | 32 | 32 | .163 | N.E. by N. | 6 | Overcast; snow squalls. | | | 23. | 63 42' | 50 10 | 28-550 | 32 | 32 | Not observed. | N.E. by N. | 6 | Overcast; snow squalls. | | | 24. | 62 36' | 51 15 | 28-519 | 32 | 32 | .163 | S.S.E. | 6 | Overcast; snow and sleet. | | | 25. | 61 30' | 53 43 | 29-069 | 32 | 31 | .134 | S.S.E. | 3 | Passing clouds; very clear. | | | 26. | 61 19' | 57 33 | 29-390 | 33 | 33 | .165 | Westerly. | 4 | Passing clouds and snow; very clear. | | | 27. | 61 48' | 64 14 | 29-538 | 33 | 32 | .163 | Southerly. | 6 | Passing clouds; very clear. | | | 28. | 61 43' | 71 13 | 29-598 | 34 | 32 | .182 | S.S.W. | 4 | Passing clouds; aurora seen. | | Mar. | 1. | 62 10' | 72 25 | 29-590 | 36 | 33 | .179 | S.westerly. | 1 | Overcast; very clear. | | | 2. | 62 44' | 76 11 | 29-501 | 36 | 33 | .146 | N.easterly. | 3 | Cloudy; very clear. | | | 3. | 64 15' | 79 44 | 29-007 | 31 | 32 | .159 | E. by N. | 5 | Overcast. | | | 4. | 63 02' | 80 27 | 28-535 | 32 | 32 | Not observed. | S.E. | 7 | Overcast; passing snow. | | | 5. | 61 41' | 84 57 | 28-714 | 32 | 31 | .160 | S.S.W. | 5 | Passing clouds; brilliant aurora. | | | 6. | 60 48' | 82 28 | 28-821 | 32 | 32 | .146 | W.S.W. | 4 | Cloudy; snow and fog. | | | 7. | 61 23' | 91 13 | 28-755 | 34 | 33 | .159 | N.N.E. | 3 | Passing clouds; very brilliant aurora. | | | 8. | 61 10' | 97 07 | 28-732 | 34 | 33 | .163 | S.easterly. | 3 | Blue sky; very clear; numerous icebergs. | | | 9. | 60 49' | 92 27 | 28-749 | 34 | 34 | .156 | S.easterly. | 3 | Cloudy and snow; aurora visible. | | | 10. | 60 03' | 95 36 | 29-048 | 32 | 32 | .125 | Southerly. | 4 | Cloudy; aurora seen. | | | 11. | 59 49' | 99 45 | 29-024 | 32 | 32 | .159 | Variable. | 4 | Cloudy; passing snow. | | | 12. | 58 31' | 98 59 | 28-512 | 33 | 32 | .159 | N.E. | 7 | Overcast; snow squalls. | | | 13. | 57 53' | 99 08 | 28-729 | 35 | 35 | .145 | S. by W. | 6 | Overcast; snow squalls. | | | 14. | 56 50' | 102 28 | 29-184 | 36 | 34 | .186 | W. ½ N. | 5 | Passing clouds; occasional snow. | | | 15. | 55 45' | 103 12 | 29-059 | 36 | 34 | .196 | W. ½ N. | 5 | Overcast and snow squalls; aurora. | | | 16. | 54 42' | 106 08 | 28-877 | 36 | 35 | .200 | W. ½ S. | 6 | Overcast; heavy squalls of snow. | MDCCXLVI. ## Table I. (Continued.) | Date | Position. | Temperature. | Hygrometer. | Wind. | Remarks. | |--------|-----------|--------------|-------------|-------|----------| | | Lat. | Long. | Corrected barom. | Dewpoint. | Elasticity of vapour. | Direction. | Force. | Remarks. | | 1845 | March | 17 | 108 09 | 29-627 | 37° | Not observed. | N.N.W. | 6 | Cloudy; passing snow squalls. | | | | | | 29-867 | 39° | 35 | S.W. by W. | 4 | Passing clouds; aurora seen faintly. | | | | | | 29-357 | 40° | 36 | W. ½ S. | 7 | Cloudy; passing squalls; aurora seen faintly. | | | | | | 30-049 | 44° | 39 | W. ½ N. | 4 | Cloudy; aurora seen. | | | | | | 29-882 | 48° | Not observed. | N.W. by N. | 6 | Overcast; misty; heavy rain squalls. | | | | | | 29-671 | 47° | 42 | N. by W. ½ W. | 2 | Overcast; misty and fog. | | | | | | 29-834 | 45° | 38 | W. by S. | 9 | Overcast; passing showers; squally. | | | | | | 29-686 | 51° | 45 | W. by N. | 7 | Overcast and squally. | | | | | | 29-996 | 51° | 44 | W. | 3 | Passing clouds; very clear. | | | | | | 30-001 | 53° | 52 | W. ¾ S. | 5 | Passing clouds. | | | | | | 29-153 | 54° | 47 | S.W. by S. | 3 | Passing clouds; very clear. | | | | | | 29-823 | 58° | 56 | W.S.W. | 1 | Overcast; wind variable. | | | | | | 29-273 | 63° | 59 | Variable. | 1 | Overcast; heavy rain. | | | | | | 30-121 | 66° | 56 | E. by N. | 4 | Passing clouds; very clear. | | | | | | 30-120 | 64° | 63 | E. by S. | 3 | Passing clouds. | | April | 1 | 35 03 | 117 56 | 30-140 | 65° | 53 | E.S.E. | 4 | Passing clouds; very clear. | | | | | | 30-184 | 64° | 58 | S.E. ½ E. | 3 | Overcast; passing showers. | | | | | | 30-181 | 65° | 52 | N.E.R. | 2 | Passing clouds. | | | | | | 30-149 | 66° | 57 | N.E. ½ E. | 3 | Passing clouds. | | | | | | 30-073 | 69° | 58 | N.W. by S. | 2 | Passing clouds. | | | | | | 29-920 | 71° | 59 | N.W. by W. | 4 | Blue sky and detached clouds. | | | | | | 29-998 | 63° | 52 | W.S.W. | 4 | Passing clouds and squally. | | | | | | 30-191 | 63° | 57 | W.S.W. | 4 | Passing clouds. | | | | | | 29-295 | 64° | 54 | E. by S. | 2 | Passing clouds; very clear. | | | | | | 30-255 | 65° | 49 | N.E. | 2 | Passing clouds. | | | | | | 30-146 | 70° | 47 | E. by N. | 3 | Passing clouds; very clear. | | | | | | 29-961 | 67° | 61 | S.W. by W. | 2 | Passing clouds. | | | | | | 30-056 | 65° | 55 | N.W. | 2 | Passing clouds. | | | | | | 30-161 | 68° | 58 | S.S.E. | 1 | Passing clouds; fine weather. | | | | | | 30-001 | 67° | 57 | W. ½ S. | 2 | Passing clouds. | | | | | | 29-818 | 64° | 60 | W.N.W. | 5 | Cloudy; strong breezes and squally. | | | | | | 29-879 | 62° | Not observed. | W.S.W. | 6 | Cloudy; squally and heavy rain. | | | | | | 30-159 | 58° | 49 | S.W. | 5 | Cloudy and squally. | | | | | | 30-330 | 57° | 50 | W.S.W. | 3 | Passing clouds and squalls. | | | | | | 30-322 | 63° | 57 | S.E. ½ E. | 0 | Passing clouds. | | | | | | 30-166 | 67° | 55 | E.N.E. | 3 | Passing clouds. | | | | | | 29-980 | 70° | 63 | N.-westerly. | 0 | Light, variable airs, and fine. | | | | | | 29-997 | 62° | 50 | W.N.W. | 3 | Cloudy and rain; variable wind. | | | | | | 30-229 | 63° | 50 | S.S.W. | 3 | Passing clouds and showers. | | | | | | 30-166 | 67° | 55 | E.S.E. | 5 | Passing clouds; wind variable. | | | | | | 30-130 | 63° | 65 | Easterly. | 5 | Passing clouds. | | | | | | 29-985 | 70° | 63 | Northerly. | 5 | Passing clouds; wind variable. | | | | | | 29-945 | 69° | 59 | W.N.W. | 5 | Overcast; passing squalls. | | | | | | 30-068 | 66° | 58 | S.S.W. | 6 | Passing clouds; strong breezes and squally. | | | | | | 30-150 | 63° | 65 | Southerly. | 5 | Cloudy; occasional squalls and rain. | | | | | | 29-985 | 70° | 63 | S. ½ E. | 1 | Overcast; drizzling rain; wind variable. | | | | | | 29-997 | 62° | 50 | Easterly. | 3 | Passing clouds. | | | | | | 30-007 | 69° | 68 | S.W. by S. | 3 | Cloudy; passing squalls and rain; wind variable. | | | | | | 29-905 | 74° | 66 | Northerly. | 5 | Overcast; strong breezes and squally. | | | | | | 29-997 | 77° | 72 | W. | 2 | Overcast; very clear. | | | | | | 29-897 | 73° | 71 | S.S.W. | 2 | Passing clouds; very clear. | | | | | | 30-028 | 72° | 69 | S.S.E. | 4 | Passing clouds; light breezes, and fine. | | | | | | 30-100 | 73° | 71 | E. by S. | 4 | Cloudy; occasional rain. | | | | | | 29-904 | 75° | 72 | E. by S. | 5 | Overcast and squally. | | | | | | 30-095 | 74° | 66 | E.S.E. | 3 | Passing clouds; fresh breezes, and fine. | | | | | | 30-051 | 76° | 73 | S.-easterly. | 2 | Passing clouds; very clear. | | | | | | 29-940 | 76° | 74 | S.S.E. | 1 | Passing clouds; light airs, and fine. | | | | | | 29-932 | 75° | 67 | E.S.E. | 4 | Overcast; very clear; strong breezes. | | | | | | 29-904 | 75° | 72 | Easterly. | 6 | Overcast; heavy rain. | | | | | | 30-132 | 75° | 72 | Easterly. | 3 | Cloudy; heavy rain and lightning. | | | | | | 29-762 | 78° | 77 | Variable. | 1 | Overcast; heavy rain. | | | | | | 29-812 | 77° | 76 | W.N.W. | 2 | Cloudy; light variable airs. | | | | | | 29-885 | 76° | 74 | W.S.W. | 2 | Passing clouds. | | | | | | 29-967 | 75° | 66 | S.W. by S. | 1 | Passing clouds. | | | | | | 30-011 | 75° | 73 | Southerly. | 3 | Passing clouds; very clear. | | | | | | 30-104 | 75° | 72 | S.W. by S. | 3 | Passing clouds. | | | | | | 30-184 | 75° | 73 | S.S.E. | 6 | Cloudy; squally, with rain. | | | | | | 30-204 | 75° | 66 | E. by S. | 5 | Overcast; squally and misty. | ### Table I. (Continued). | Date | Position | Corrected barom. | Temperature | Hygrometer | Wind | |------------|----------|------------------|-------------|------------|------| | | | | | Dew. point | Elasticity of vapour | Direction | Force | Remarks | | Lat. | Long. | | | | | | | | | 1845. | | | | | | | | | | May 25 | At anchor | 30-204 | 74 | 73 | 63 | -570 | E. by s. | 4 | Passing clouds and squalls. | | 26 | Port Louis | 30-190 | 77 | 72 | 63 | -570 | s.e. by e. | 3 | Passing clouds. | | 27 | Mauritius | 30-169 | 76 | 72 | 59 | -505 | s.e. by e. | 3 | Cloudy; squally and rain. | | 28 | | | | | | | | | | 29 | -20 50 | 55 32 | 30-160 | 78 | 74 | 62 | Easterly. | 3 | Passing clouds. | | 30 | -21 50 | 53 30 | 30-144 | 77 | 74 | 64 | N-easterly. | 5 | Passing clouds. | | 31 | -23 32 | 51 59 | 30-107 | 78 | 76 | 67 | Easterly. | 3 | Passing clouds; moderate breezes and fine. | | June 1 | -25 59 | 49 28 | 29-949 | 75 | 74 | 70 | Northerly. | 7 | Cloudy; heavy squalls and rain. | | 2 | -26 55 | 49 11 | 29-974 | 73 | 72 | 60 | S-westerly. | 6 | Cloudy; strong breezes and squalls. | | 3 | -26 23 | 48 25 | 30-076 | 70 | 70 | 54 | S by e. | 6 | Passing clouds; heavy squalls. | | 4 | -27 14 | 45 59 | 30-260 | 68 | 70 | 54 | S-easterly. | 4 | Passing clouds; very clear. | | 5 | -28 26 | 42 48 | 30-087 | 69 | 71 | 64 | Easterly. | 5 | Overcast; heavy squalls and rain. | | 6 | -28 46 | 41 56 | 30-006 | 68 | 70 | 58 | W.S.W. | 5 | Overcast and squally. | | 7 | -28 38 | 40 18 | 30-201 | 70 | 69 | 58 | S | 6 | Passing clouds; strong breezes. | | 8 | -28 58 | 37 49 | 30-298 | 72 | 70 | 54 | Easterly. | 3 | Passing clouds; wind variable. | | 9 | -30 23 | 35 24 | 29-986 | 71 | 71 | 66 | N-S.E. | 6 | Squally; with heavy rain and lightning. | | 10 | -31 03 | 33 56 | 29-892 | 68 | 70 | 58 | W | 8 | Cloudy; heavy squalls and rain. | | 11 | -30 27 | 33 41 | 30-093 | 66 | 68 | 54 | S.S.W. | 3 | Cloudy and rain. | | 12 | -30 35 | 33 13 | 30-215 | 65 | 67 | 51 | Southerly. | 3 | Passing clouds and rain. | | 13 | -31 10 | 31 28 | 30-490 | 65 | 67 | 47 | S.S.E. | 3 | Cloudy and squally, with lightning. | | 14 | -33 03 | 29 23 | 30-472 | 68 | 69 | 57 | Northerly. | 3 | Passing clouds. | | 15 | -34 51 | 26 46 | 30-351 | 71 | 70 | 56 | Northerly. | 3 | Passing clouds; hazy. | | 16 | -35 45 | 23 28 | 30-128 | 70 | 69 | 55 | N.N.W. | 2 | Passing clouds; very clear. | | 17 | -35 40 | 21 30 | 30-026 | 63 | 66 | 58 | Northerly. | 2 | Cloudy; light variable airs. | | 18 | -35 05 | 20 44 | 30-149 | 60 | 58 | 56 | W.N.W. | 1 | Passing clouds; in soundings. | | 19 | -35 08 | 20 24 | 30-275 | 58 | 58 | 53 | S.W. by W. | 1 | Overcast. | | 20 | -34 55 | 19 27 | 30-406 | 58 | 58 | 50 | S.E. | 1 | Passing clouds; very clear. | ### Table II. | Date | Lat. | Barometer corrected. | Tension of vapour | Gaseous pressure | Temperature of air | |--------------------|------|----------------------|-------------------|------------------|-------------------| | 1845. | | | | | | | January 10 to 16. | -36 | 35 | 30-148 | -453 | 29-695 | 62 | | 17 to 23. | -46 | 02 | 29-593 | -261 | 29-332 | 45 | | 24 to 30. | -55 | 37 | 29-280 | -170 | 29-110 | 34 | | January 31 to February 6. | -62 | 40 | 29-111 | -184 | 28-927 | 33 | | February 7 to 13. | -66 | 47 | 29-354 | -141 | 29-213 | 30 | | 14 to 20. | -64 | 47 | 28-828 | -164 | 28-664 | 33 | | 21 to 27. | -62 | 36 | 28-985 | -156 | 28-829 | 32 | | February 28 to March 6. | -62 | 20 | 29-153 | -162 | 28-991 | 34 | | March 7 to 13. | -59 | 54 | 28-843 | -154 | 28-689 | 34 | | 14 to 20. | -53 | 33 | 29-168 | -209 | 28-959 | 38 | | 21 to 27. | -44 | 23 | 29-834 | -289 | 29-545 | 50 | | March 28 to April 3. | -35 | 41 | 30-169 | -454 | 29-715 | 63 | | April 4 to 10. | -35 | 03 | 30-103 | -439 | 29-664 | 66 | | 11 to 17. | -35 | 03 | 29-980 | -463 | 29-517 | 66 | | 18 to 24. | -35 | 06 | 30-136 | -427 | 29-709 | 63 | | April 25 to May 1. | -27 | 41 | 30-066 | -498 | 29-568 | 68 | | May 2 to 8. | -23 | 07 | 29-971 | -564 | 29-407 | 73 | | 9 to 15. | -20 | 35 | 29-947 | -636 | 29-311 | 75 | | 16 to 22. | -20 | 53 | 29-852 | -667 | 29-185 | 76 | | 23 to 29. | -20 | 18 | 30-124 | -566 | 29-558 | 76 | | May 30 to June 5. | -25 | 41 | 30-037 | -561 | 29-476 | 73 | | June 6 to 12. | -29 | 50 | 30-060 | -473 | 29-587 | 69 | | 13 to 19. | -34 | 23 | 30-242 | -429 | 29-813 | 65 | | 20. | -34 | 55 | 30-378 | -368 | 30-010 | 58 | ### Table III | Lat. | Corrected barometer. | Tension of vapour. | Gaseous pressure. | Temperature of air. | Number of observations | |------|----------------------|--------------------|-------------------|---------------------|-----------------------| | -20°35' | 29.981 | -623 | 29.358 | 76 | 126 | | -24°24' | 30.004 | -562 | 29.442 | 73 | 84 | | -28°45' | 30.063 | -486 | 29.577 | 68 | 84 | | -35°15' | 30.151 | -433 | 29.718 | 63 | 258 | | -45°12' | 29.710 | -275 | 29.435 | 47 | 84 | | -56°21' | 29.097 | -178 | 28.919 | 35 | 126 | | -62°32' | 29.083 | -167 | 28.916 | 33 | 126 | | -65°47' | 29.091 | -153 | 28.938 | 31 | 84 |