A B E 



The Ar;;u'ivnt for tlic Longitude ii, Z,anf. Sun — 

 /.«»f. 5/j.-. The Arj^iiir.ent for llic Latitude is, Long. 

 Suft—l-on". Sl.tr — 3 %n/. 



To find tlic alerrt 



,•«/;.« in |'°^"?;|,^f}, multiply the 



quantities taken from this table by -J ^^^^ J- of the 



liar's latitude. 



Ex. Let the longitude of the fun be 7' 5° 18', 



the long, of a ilar 5' 18° 14', and its latitude 31° 10'. 



r 5° 18' 

 5 18 14 



>7 

 31 



10 Sec. 



-13" 

 I 



62 

 169 



ylbenatlon in longitude 



!• 17° 4' — 3' = io« 17° 4' 

 31 10 Sine 



— 15 , 92 Produft. 



-i4"/J5 

 0,5175 



Aberration in latitude — 7i58 Produdl. 



To find ^vtAherration in declination and right afccnfion. 

 Dr. Bradley has annexed to his theory the rules or formulas 

 for tliispuipofc; and thefc ruJi.shave been varioufly de- 



ABE 



nionftrated, and reduced to other praAical fornu by M. 

 Clairaut, in the Mem. of the Acad, of Sciences for 1737 ; 

 by Mr. Simpfon in his Effays in 1 740 ; by M. Fontaine des 

 Crates in 1744; by M. Euler, Mem. Acad. Berlin, torn. 

 ii. p. 14. &c. ; and by fevcral other perfons. The refults of 

 them are as follow : — The greatell aberration in decUiinlion is 

 equal to 20", multiplied by the fine of the angle of poiitlon 

 A at the liar, and divided by the fine of B, the difference 

 of longitude between the fun and (lar, when the aberration 

 ill dechnation is nothing. And the aberration in declina- 

 tion at any other time will be equal to the greateft aberra- 

 tion multiplied by the fine of the difference between the fun's 

 place at the given time, and his place when the aberration is 

 nothing. Alfo the fine of the latitude of the ilar is to ra- 

 dius, as the tangent of A is to the tangent of B. The 

 greateil aberration in right aj'eenjion is equal to 20" multi- 

 plied by tiie cofine of A, the angle of polition, and divided 

 by the fine of C, the difference in longitude between the 

 fun and liar, when the aberration in right alcenfion is no- 

 thing. And the aberration in right afcenfion at any other 

 time, is equal to the greateft aberration multiplied by the 

 fine of the difference between the fun's place at the given 

 time, and his place when the aberration is nothing. Alfo, 

 the fine of the latitude of the liar is to radius as the cotan- 

 gent of A to the tangent of C. Hutton's Mathem. Dift. 

 Art. Aberration. 



Mr. Vince has purfucd the method given by M. Cagnoli 

 in his Trigonometry, as the moft convenient in praftice, and 

 fubjoined the tables computed by M. de Lambre in this way. 



We (hall here annex the tables, referring to Mr. Vince's 

 Aftronomy, [ubi infra,) for the proceffes, whence the ex- 

 preffions for the aberration in right afcenfion and declination 

 on which they are formed have been deduced. 



