rOL. XIII.] PHILOSOPHICAL TRANSACTIONS. 63Q 



from the following observations, of the distances between the two planets, in 

 October l682: 



gd ij^h si"^. , ,. between their centres ° 34' 54' 



54 .... the same repeated 34 48 



12 13 49 .... between the centres 16 2 



54 .... repeated 16 4 



14 3 . . . . between the near limbs 15 22 



17 14 10.... between the centres 20 9 



17 ....repeated 20 12 



21 ....again 20 14 



25 .... between the near limbs .... 19 44 



33 .... between the remote limbs 20 37 



15 9 . . . . Saturn from Castor's heel 48 32 25 



14 .... Jupiter from the same 48 45 5 



17 .... repeated 48 45 20 



20 .... Saturn from the same 48 32 20 



50 .... between the centres again 20 30 



1915 41 ... . between the further limbs 26 2 



45 .... their centres 25 37 



47 .... their near limbs 25 11 



22 18 25 their centres 33 19 



29 .... repeated 33 26 



The distances between the planets were measured with the micrometer and a 

 16-foot glass; from the fixed stars with the sextant: those of the 12th day by 

 my assistant, myself being then very ill of the stone; the rest by myself. 



On the 22d day the planet Jupiter was in consequence of Saturn, something 

 less distant from him then he had been observed on the 5th day, near the same 

 hour. Hence the middle time between these observations is pointed out for the 

 time of their true conjunction. But to determine it more accurately, I shall 

 examine the observations made with the sextant on the 17 th day, which being 

 nearest the time are most proper for this purpose. 



The correct longitude of the heel of Castor is now 25 0° 50' 42^, its latitude 

 5 1' 40" south. The latitude of Saturn by the Caroline tables 56' 20", of Jupiter 

 41' 30", both north. 



By the assumed latitude of Saturn 56' 20", and his distance from the heel of 

 Castor, observed and corrected, 48° 32' 30", I find their difference of longitude 

 48° 30' 37^^; therefore Saturn in Leo 19° 21' 19". 



By the latitude of Jupiter assumed 41' 30', and his distance from the star 48** 



