1835.] First Astrommer- Royal. 403 



books, to which I was, till then, a stranger. He was a 

 person of great humanity and judgment, a good Algebraist, 

 and endeavoured to draw me into the study of Algebra, by 

 proposing little problems to me : which, having not long 

 before made myself acquainted with Euclid, I gave him 

 geometrical resolutions to ; and never troubled myself with 

 Algebra till I came to London, where I found every small 

 pretender to mathematics set up for an Algebraist. 



This eclipse I observed afterwards : but, not being fur- 

 nished with proper instruments, nor yet acquainted with 

 the best way of observing, I cannot think the observations 

 exact enough to be published. 



Another eclipse of the Sun, happening two years after, 

 on the 25th of October, 1668, I calculated the times of the 

 appearance from the Caroline Tables; and afterwards ob- 

 served it. But, not being yet furnished with convenient 

 instruments for measuring and correcting the times, I could 

 not believe it accurate enough to be published : though I 

 found by it that the tables differed very much from the 

 heavens. 



The French Observatory was built this year, and Signor 

 Cassini called from Italy to direct it : who now published 

 his Tables for finding the Eclipses and Configurations of 

 Jupiter's Satellites. These fell into my hands some three 

 or four years after ; and were of good use to me, however 

 faulty when I began to observe them. 



In the following years, 1669 and 1670, 1 compared Jupiter 

 and Mars with some fixed stars, near which they passed : 

 but, the observations (being made with short glasses of two 

 feet, and only by estimation of the planets' distances from 

 them, and comparing them with the small distances of fixed 

 stars derived from Tycho's places) were not to be relied on. 

 Only, I learnt by them that those distances were faulty : 

 and the planets' places much different from those given in 

 the ephemerides. 



Mr. Street's equation of natural days being very much 

 different from that used by Tycho Bullialdus, and Wing, I 

 had spent many thoughts upon it, at the same time as I 

 remember I was calculating the solar eclipse : and at last 

 found that supposing the earth's revolution to be equable 

 about her axis, it could be no other than the difference of 



2d2 



