A Yorkshire Rector of the Eighteenth Century. 23 



might some time or other be discovered.'* a prediction whicli 

 was afterwards verilied by the brilhant star-work of Herscheh 



Again, Michell in his memoir of 1767 was the first to pubHsh 

 correct views in regard to the telescopic visibility of small 

 stars, which he showed to be dependent on the area of the 

 aperture of the instrument. ' Assuming the diameter of the 

 pupil of the eye to be equal to one third of an inch, and roughly 

 estimating the quantity of light lost in passing through the 

 telescope, he was enabled to compare the distance of the 

 faintest stars seen in a telescope of given aperture, with the 

 distance of those barely visible to the naked eye.'f The 

 principle thus initiated by him for estimating the distribution 

 of stars at different distances in the depths of space was 

 afterwards successfully employed by Herschel. 



From the outline which I have now given of the scientific 

 labours of John Michell it will be apparent that he must have 

 been a singularly gifted philosopher. Among his contem- 

 poraries during the latter half of the eighteenth century he 

 seems to stand out as conspicuous for the wide range of his 

 investigations, and for the originality both of his methods of 

 research and of the views to which they led him. Moreover, 

 he is now seen to have possessed' the faculty of reaching, in 

 more than one branch of enquiry, intuitions which curiously 

 anticipate results arrived at by later generations. On every 

 line of research which he entered he left the mark of his genius. 

 His mechanical skill enabled him to devise and construct 

 with his own hands the instruments or apparatus with which 

 he could experimentally illustrate or test the theoretical 

 conclusions to which he came. In Geology, in Physics, and 

 in Astronomy, he was a true pioneer. 



With all this capacity for original research of the highest 

 quality, he combined in no common degree the gifts of modesty 

 and caution. Even when tolerably certain of the soundness of 

 a deduction, he would not go farther than to state its probab- 

 ility, until he could, where possible, demonstrate its certainty 

 by careful experiment. He was never in a hurry to publish 

 his observations, though ever ready to communicate them to 

 a fellow-worker interested in the same branch of enquiry. 

 There can be little doubt that much of his quiet work at 

 Thornhill rectory was never published. He pursued science 

 as a pure labour of love. For personal credit or fame he 

 appears to have cared little. Though he stood high in the 

 esteem of his contemporaries, it would seem that his distinction 

 has been somewhat overlooked b^- his successors, and that 

 some of his discoveries have been attributed to others. 



* R. Grant, op. cit., p. 559. 

 t Grant, op. cit., p. 543. 



1918 Jan. 1, 



