EAELY LIFE AND STUDIES. 255 



of the lens under these circumstances has been shown 

 to vary from six to ten millimeters. Young's theory 

 of the adjustment of the eye has been therefore com- 

 pletely verified. But it is still a moot point as to what 

 the mechanism is by which the change of curvature is 

 produced. Young thought that it was effected by the 

 muscularity of the lens itself. The muscles, however, 

 would require nerves to excite them, and it would be 

 hardly possible, in the transparent humours of the eye, 

 for such nerves to escape detection. They, however, 

 have never been detected. 



While passing through Bath in 1794 Young, at the 

 instance of Dr. Brocklesby, called upon the Duke of 

 Richmond. The impression made by Young at this 

 time may be gathered from a note addressed by the 

 Duke to the Doctor in these terms : 'But I must tell 

 you how pleased we all are with Mr. Young. I really 

 never saw a young man more pleasing and engaging. 

 He seems to have already acquired much knowledge in 

 most branches, and to be studious of obtaining more. 

 It comes out without affectation on all subjects he talks 

 upon. He is very cheerful and easy without assuming 

 anything ; and even on the peculiarity of his dress and 

 Quakerism, he talked so reasonably, that one cannot 

 wish him to alter himself in any one particular. In 

 short, I end as I began, by assuring you that the 

 Duchess and I are quite charmed with him.' The Duke, 

 then Master of the Ordnance, was a very competent 

 man. He was well acquainted with the instruments 

 med in the great Trigonometrical Survey under his 

 control. He offered to Young the post of private 

 secretary. Young's acceptance would have brought 

 wilhin his reach both honour and emolument. But to 

 his credit be it recorded he refused the post, because 



