On the new method of determining the longitude by the culmination of the moon and stars being a paper read before the Astronomical society of London. To which are now added an appendix, and a list of stars, applicable to the purpose, for the year 1825 / By Francis Baily.

  • Francis Baily
Date:
1824
Catalogue details

Licence: Public Domain Mark

Credit: On the new method of determining the longitude by the culmination of the moon and stars being a paper read before the Astronomical society of London. To which are now added an appendix, and a list of stars, applicable to the purpose, for the year 1825 / By Francis Baily. Source: Wellcome Collection.

    19/50 page 17
    -}-03,381 = 26“ 40s,431. The true right ascension of the moon, for the apparent times above mentioned, will be respectively c = 22h 46ra a— 197° 48' 18,4 x = 8 16 a = 191 8 7 ,1 (C — x) = 14 30 (a-a) = 6 40 11,3 — = 2*17398 a — a Whence the final equal equation will be X — 26ra 40s,431 ^~ x 2’17398 — 1*) = 14h 5ra 36s,83 which is the longitude of Paramatta west of Paris : and this, being sub¬ tracted from 24h, will give 9h 54m 23s, 17 for the longitude east. If from this value we deduct the difference of meridians between Paris and Manheim, found as above, we shall have (9h 54m 23s,17 — 24m 24s,23) = 9h 29m 58s,94 for the difference of meridians between Manheim and Paramatta. 27. Hitherto the observations have been confined to the western border only of the moon : but, it would evidently add much to the accuracy of the results if the transits of the stars were compared also with the eastern bor¬ der. This suggestion has been attended to by M. Schumacher ; and it is his intention in future to extend his list of stars through a greater portion of each lunation, in order that observers may make comparisons with each border of the moon. The method of computation will be precisely the same; atten¬ tion being paid to the double sign in the formula (A). Whether any advan¬ tage could be gained by observing particular spots on the moon, must be left to future trial. Owing to the difficulty of identifying such spots, as well as to their constant change of position (arising from the libration of the moon) such a plan would be impracticable at observatories very distant from each other; and ought not to be adopted, even in those situated near each other, without considerable caution. 28. I would also remark that it was, at first, the practice of astronomers, in recording observations of this kind, to state merely the differences observed. But, they have since adopted the more satisfactory method of recording the exact time of each observation (in the order in which they occur); corrected for the error of the clock and the deviation of the instrument: to which are usually annexed (for the reasons hereafter to be mentioned) the number of wires at which each observation has been made. It would be a still further improvement of the method of recording and publishing such observations, Astron. Soc. of Lond. vol. ii. D
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