352 Mr, WoLt A STOMAS Dejcription, &c. 



tion, aiid its fine in another calumii for right afcenllon, and 

 under each the conftant fm. a-\-q^ and the arithmetical compl. 

 of fin. ii ; thefe heing added together will make two fums, 

 for the comparative obfervations of every ftar which may pafs 

 your field ; and, iinlefs your field be very large, and the decli- 

 xiation of the flars very great, if to the column for declination 

 you add the cofine of declination of the center of your field, it 

 will adapt itfelf to all the. produds. 



FRANCIS WOLLASTON. 



Charter-hoiife-Square, 

 March 15, 1785. 





POSTSCRIPT. 



SINCE the delivery of this Paper, it has occurred to me, 

 t,hat it may fometimes be convenient to know the angle of^ 

 deviation from the true equatorial pofition in the new fyftem of 

 wires. This is to be deduced nearly in the fame manner as in 



the rhombus ; for — — = tang, q. By this angle any obferved 



differences in right afcenfion may be corredled : for the dif- 

 ference in declination between any two ftars (or their dif- 

 ference from the angle) multiplied by fin. q, will give the cor- 

 redion required. I 



