■©58 "-■■.:' ^' ■■ A NEW METHOD OF 



ARn. moon's centre by last transit, ... ,. ... 21: 42: 31. 8 



Ditto first ditto, ,.. 21:42:30.- 8 



Mean, 21:42:31. 3 



Now the time at Greenwich, when the moon's centre had^^ 



this ARn. is computed to be, J 



And the time at Prome is, 6 : 1 1 : 23 



23: 50: 45 



Longitude, G: 20: 38 



Now the true Longitude, as deduced from lunar transits, is,.. 6 : 20 : 40 



The practical superiority of this method over that given by several writers, 

 is obvious, for the two consecutive transits of the sun, one preceding, and the 

 other subsequent to the moon's transit, will determine the correction for rate, 

 and an horizontal deviation of 5' in the transit instrument, will superinduce 

 an error of only (y^. 5 in right ascension at the most. 



Another method equally accurate may be adopted, but it Is more tedi- 

 ous. In this method, we may deduce the apparent time from the moon's 

 right ascension ; independently of the correction for acceleration, or retarda- 

 tion of solar on apparent time, but then we must use the siui's riglit ascen- 

 sion as an element. Or we may compute the apparent time, in the way shown 

 -in the example. Neither of these methods are so commodious as the first 

 method. 



PROME OBSERVATORY, 

 : i 17th January, 1826. 



' Sun passed meridian, ... 00: 08: OJ. 6 



• Moon, 6: 42: 55. 2 



6 : 34 : 47- 60 



