MICROSCOPIC VISION. 145 



3. The suggestion of homogeneous immersion. 



It is refreshing to turn from the pedantic writings of 

 Dr. Pigott to the manly utterances of the Rev. S. Leslie 

 Brakey. If language be defined as a means of enabling 

 others to understand the speaker or writer's thoughts, then 

 S. Leslie Brakey has the gift of language in no small degree, 

 for in the whole of the E.M.S. Journals nowhere do we 

 meet with such simplicity of style, clearness of expression, 

 and masterly handling of the subject. Not only is Mr. 

 Brakey a literary scholar, but he shows himself to be a 

 mathematician of no small power. But strange as it may 

 appear. Dr. Pigott is in the main right, while Mr. Brakey is 

 wrong. 



The following passage from one of Mr. Brakey 's letters 

 will show you what his opinion of Dr. Pigott's paper 

 was : — 



" I have said that the question was obscured by the intro- 

 duction of things irrelevant. The history of Claudius 

 Ptolemy is no more to the point than the history of Claudius 

 Csesar or Claudius Lysias. No more are the laws of refrac- 

 tion and reflexion, repeated (for about the twentieth time), 

 because these laws are ' first truths,' and are known to every 

 one, and never are, nor ever have been, denied by any one 

 great or small. There is, no doubt, a sense in which this or 

 any other optical question may be said to depend upon 

 them ; the same sense in which we may say that a question 

 about the nutation of the earth's axis or the motion of the 

 moon's apse depends upon the multiplication table. These 

 laws are brought in on every occasion with much arithmetic 

 and mathematics done with Greek. This display of learning 

 seems to have impressed his readers so much that even 

 skilful observers fear to trust their own faculties against 

 mathematics so original and profound. No doubt it is very 



