258 OBSERVATIONS OF THE ECLIPSE 



and the calculation made upon the same principles, only using 

 the distance of the centres, instead of the sum of the semidi- 

 ameters. — Those which I used, are marked numerically in the 

 margin, en each side of the nearest observed distance between 

 the points of the cusps: — the corresponding numbers answer 

 to the two observations for which a particular calculation was 

 made. — This arrangement furnished me with twelve separate 

 determinations, from the mean of which it appeared, that up- 

 on the supposition of the longitude of Lancaster being 5" 5' 6" 

 and the latitnde 40° 2' 36" the moon's longitude as deduced 

 from Mason's tables will be 1' l" too great, and the latilude 

 1 1" too small: — But by the eclipse, independently of the mea- 

 sures taken by the micrometer, the moon's longitude by the 

 tables will be 52" too great, and her latitude 3" too small. — 

 If, however, the tables should be found correct, at the royal 

 observatory of Greenwich, by the observation of the same eclipse, 

 or other methods, the longitude of Lancaster must be reduced 

 about 1' 33" in time, by the beginning and end of the eclipse, 

 and still more by the measures taken with the micrometer. — 

 It is probable that the error is partly in the tables, and partly 

 in the assumed longitude of Lancaster. 



By the beginning and end of the eclipse, the true conjunc- 

 tion under the meridian of Lancaster, was at 1 l h 15' 31" A. M. 

 apparent time; and by the measures taken with the microme- 

 ter at ll b 15' 47". 



In making the calculations I have allowed 5" for inflexion, 

 and irradiation, and diminished the altitude of the pole 14' 38", 

 and the moons horizontal parallax 6" on account of the sphe- 

 roidal figure of the earth. 



I am, dear sir, with great esteem, 



your friend and humble servant, 



ANDREW ELLICOTT. 



Robert Patterson Esq. 

 V. P. of the A. P. S. 



I 



