Observations of the Eclipses of the First Satellite of Jupiter, communicated by His Excellency William Burnet, Esq; Governor of New York, F. R. S.

It lived with me about a Fortnight, but I could never perceive that it beat, after it was confin'd in the Box. II. Observations of the Eclipses of the first Satellite of Jupiter, communicated by his Excellency William Burnet, Esq; Governor of New York, F. R. S. These Observations were made in the Fort of New York, for determining the Longitude of that Place by us, William Burnet, Cadwallader Colden, James Alexander, and calculated by Cadwallader Colden. The Latitude of the Fort, was formerly determin'd to be $40^\circ 40'$. August the 9th, 1723. Time of Emerion at London, according to Mr. Pound's Tables, reduced to apparent Time | H. | M. | S. | |----|----|----| | 16 | 09 | 25 | Time as it was seen at New York | H. | M. | S. | |----|----|----| | 11 | 10 | 43 | Difference of Meridians | H. | M. | S. | |----|----|----| | 4 | 58 | 42 | I neglected to write down the Altitudes which were taken of the Sun, for correcting the Clock. August August the 25th. | Altitude of the Sun's Upper Limb | Time by the Clock | Time by Calculation | |---------------------------------|-------------------|--------------------| | 0° 1' | H. 1° | H. 1° | | Sun's Declin. | 549 30 00 | 10 17 52 | 10 17 28 | | 6° 55' | 51 13 30 | 10 33 10 | 10 32 8 | | Aug. 26. | 46 24 00 | 9 57 40 | 9 56 25 | | Sun's Declin. | 47 50 00 | 10 8 22 | 10 6 57 | | 6° 33' | | | | H. 1° Time of Emersion by Mr. Pound's Tables 14 31 25 Equation of Time to be added 00 01 22 14 32 47 Time observ'd by the Clock 09 35 14 The same corrected 09 34 14 The Difference of Meridians 04 58 33 This I look upon as the most distinct and best Observation. September the 10th. | Altitude of the Sun's Upper Limb | Time by the Clock | Time by Calculation | |---------------------------------|-------------------|--------------------| | 0° 1' | H. 1° | H. 1° | | Sun's Declin. | 33 21 | 09 01 00 | 09 00 16 | | 49' | 34 06 | 09 06 01 | 09 04 49 | | Sept. 17th | 17 17 | 04 21 40 | 04 21 44 | | Sun's Declin. | 15 15 | 04 33 05 | 04 32 47 | | 1° 54' | | | | Time Time of Emersion by the Clock September 10th | Time by the Clock | H. ' " | |-------------------|-------| | 08 00 10 | Time of Emersion by Mr. Pound's Tables | Time by the Clock | H. ' " | |-------------------|-------| | 12 50 36 | Equation of Time to be added | Equation of Time | H. ' " | |------------------|-------| | 00 06 54 | Corrected Time at New York | Corrected Time | H. ' " | |------------------|-------| | 12 57 30 | | 07 59 08 | Difference of Meridians | Difference | H. ' " | |------------------|-------| | 04 58 22 | June 26th, 1724, Altitude of the Sun's Upper Limb. | Altitude | Time by the Clock | Time by Calculat. | |-----------------|-------------------|-------------------| | 0° | 09 48 03 | 09 43 37 | | Sun's Declin. | | | | 23° 7 | 10 09 40 | 10 05 05 | | June 27th, | | | | Sun's Declin. | | | | 22° 26 | 10 27 43 | 10 27 05 | | | 10 40 00 | 10 39 27 | June the 26th, Time of Immersion by the Clock | Time by the Clock | H. ' " | |-------------------|-------| | 11 41 12 | Time of Immersion by Mr. Pound's Tables | Time by the Clock | H. ' " | |-------------------|-------| | 16 43 02 | Equation of Time to be subtracted | Equation of Time | H. ' " | |------------------|-------| | 00 04 26 | Time at New York corrected | Corrected Time | H. ' " | |------------------|-------| | 16 38 36 | | 11 40 15 | Difference of Meridians | Difference | H. ' " | |------------------|-------| | 04 58 21 | The Mean of all these Observations is $4^h\ 58'\ 30''$ which agrees to $3''$ with that Observation, which I thought the most exact, and therefore the Longitude of New York, is nearly $74^\circ\ 57'\ 30''$ West from London. The Variation of the Magnetick Needle was observ'd, this Year, to be $7^\circ 20'$ West. Philip Wells, Surveyor General of this Province, in the Year 1686, observ'd it to be $8^\circ 45'$; by which, it appears to decrease about $1^\circ 25'$ in 38 Years, or a little more than two Minutes in a Year. III. A New Contrivance for taking Levels, by the Reverend John Theophilus Desaguliers, L. L. D. R. S. S. That the Air Thermometer is also a Barometer, has been observ'd long ago; and, because the Liquor in it will rise and fall, as well by the Change of the Weight of the Air, as by the Air's Rarefaction by Heat and Cold, this Instrument has no longer been made use of as a Thermometer, and, in its stead, Spirit of Wine Thermometers, hermetically seal'd, have been us'd ever since. But, because the Errors of the Air Thermometer (or its Difference from the Spirit Thermometer) depend only upon the Change of the Weight of the Atmosphere from what it was, when the two Thermometers were set at the same Degree of their respective Scales; the late Dr. Hook contriv'd an Instrument, that he call'd a Marine Barometer, made of a Combination of the two abovemention'd Thermometers; in such Manner, that a third Scale being made use of, to observe the Difference of the two Thermometers, thereby the Change of the Air's Gravity, and consequently Storms, Rains, and fair Weather, might be foretold at Sea, where the Quicksilver Barometer becomes useless by the flanking of the Ship.