MATHEMATICAL P A P E K S. 27 



from wliicli we may find Mercury's horary motion upon the 

 Sun's disc, with respect to the ecUptick, at the* beginning of 

 the transit, 5' 4r. 059 ; and at the end, 5' 50". 955. This 

 was the compound motion of the Sun and Mercury ; Mer- 

 cury's motion being retrograde. If therefore, we substract 

 the Sun's horary motion, Ave shall have Mercury's gcocen- 

 trick horary motion in longitude, at the beginning of the 

 transit, 3' 18''. 359; and at the end, 3' 20''. 255. 



Mercury's helioccntrick motion in longitude, from 

 8'^ 24' 4", the time of the first external contact, till 10'^ 39' 31", 

 the time of the ecliptick conjunction, by the tables, was 

 33' 50". 1, making 28' 9". 9 from the Sun, and 13' 8". 29 for 

 his motion upon the Sun's disc, which makes his gcoccntrick 

 motion in longitude 7' 28". 09. The similar motions, from 

 10"^ 39' 31" to 1'' 17' 36", the time of the second external 

 contact, were 39' 35". 2, 32' 58". 2, 15' 22". 77 and 8' 45". 77. 



Mercury's horary motion in latitude, at the bemnnin;^ of 



o "o 



transit, was 51". 404 ; and at the end, 51". 685 ; and from 

 S'^ 24' 4" to 10^ 39' 31'; 1' 56". Oil ; and from 10^ 39' 31", to 

 1^ 17' 36'', 2' 16". 115, decreasing. 



The longitude of the Sun therefore, and Mercury's gco- 

 ccntrick longitude by the tables, at 10^ 39' 31", being 

 T 13^ 40' 56". 5 J and the latitude of Mercury, 7' 27". 95, we 

 shall find," 



F 



At the time of the first ^external contact, viz. 8'^ 24' 4" a. m. 



7^ 13^^ 35' 16". 3 

 ck lon-itude. 7 13 48 24. 59 



gitude 



^ 's geocentrick latitude. 

 O's right ascension. 



9 23. 961 



221 7 34 



Right 



