1835.] First Astronomer- Royal. 406 



Townley's micrometer, and undertook to furnish me with 

 telescope glasses at moderate rates. I left monies in Mr. 

 Collin's hands to pay for them : and in my return visited 

 Dr. Barrow, and Mr. Newton, the Lucasian Professor of 

 Mathematics at Cambridge; and Dr. Wroe, then a fellow 

 of Jesus College there, with whom I corresponded frequently 

 the four following years. Entered myself at Cambridge in 

 Jesus College. 



About this time Mr. Newton was engaged in experiments 

 about Light and Colours, and the improvement of tele- 

 scopes ; of which I had some account sent me by Mr. Collins : 

 though his theory and the description of his new contrived 

 telescope came not out till February 1671-2; when it was 

 published [in the Transactions^ No. 80. 



I could not at first yield to this theory : but, upon trial, 

 found all the experiments succeeded as he related them ; 

 which kept me silent and in suspense. For, I could never 

 think that whiteness was a compound of all the different 

 sorts of rays of light mixed ; because I found always that 

 what he called whiteness was only sun-light, or solar rays : . 

 and that when the rays, which he called whiteness, were 

 mixed with the blue, they formed a green ; which showed 

 they were of the nature of yellow. 



My first telescope glasses were not procured me till about 

 Michaelmas, 1670 : but the eye-glasses suited not with 

 them. And both Mr. Jonas Moore and Mr. Collins having 

 employments that kept them continually in business, I 

 could not procure such eye-glasses for them till the next 

 autumn, 1671. [Here the description of Mr. Townley's 

 micrometer is to be inserted ; with the tables for turning 

 the revolves and parts, into minutes and seconds : as also 

 the figures and descriptions of my own, with the like 

 tables.] 



In the mean time, some affairs of my father's requiring 

 it, in the month of June this year, I made a journey into 

 Lancashire, and called at Townley, to visit Mr. Christopher 

 Townley, who happened to be then in London. But, one 

 of his domestics kindly received me, and showed me his 

 instruments, and how his micrometer was fitted to his 

 tubes : and from this time forward we often conferred by 

 letters. I procured Mr. Gascoigne's and Crabtree's papers 



