412 LIMITS OF OPIICIL CAPACITY OF THE MICROSCOPE. 



Microscopical Science, and the Transactions of the Eoyal Society 

 during present and preceding years. Of these, one series of papers 

 published by Dr. R. Pigott claims to be a mathematical exposition 

 of optical latvs governing the divergence and dispersion of rays of 

 light transmitted through different kinds of glass. Another series 

 of papers by Mr. Wenham takes the practical direction to which 

 English microscopists mostly incline. The communications of 

 Mr. Sorby have enriched microscopic science with the most ingenious 

 and successful applications of spectrum analysis that any country 

 can boast. To all these gentlemen the English student may feel 

 equally indebted for their respective labours. And the mention of 

 these in juxtaposition with the work of so great an authority as 

 Prof. Helmholtz and so conscientious a workman as Prof. Abbe, is 

 not only due as a recognition of the individual services, but also 

 as a proof of the higher direction of study now being pursued in 

 England by amateur microscopists. As a humble member of this 

 numerous class, the present writer ventures to refer to the early 

 date of Mr. Wenham's communications when he stood almost alone 

 as the 'pioneer of a future micrographic science, and to bear 

 thankful testimony to the practical experience and sterling value of 

 all that he has written. And he also cordially recognises the high aim 

 and zealous study of Dr. E. Pigott, the direction of whose labours 

 must ultimately prove most serviceable to all who desire to 

 understand the real power and possible perfection of their favourite 

 instrument. Any unfair spirit of criticism of matters so little 

 appreciated by some of his critics is to be earnestly deprecated. 

 One can only regret, whilst profiting by the opportunity of hearing 

 all sides of a question, to be reminded of the woeful sentiment 

 " tantcBJie celestihus iroeP The vexatious partisanship of '* aperture " 

 and the disputed estimates of the performance of lenses constructed 

 by this or that maker, must appear as overstrained and even 

 ridiculous to the optician who can best guage his own or any other 

 maker's work, as to those who care only to understand the 

 principles of construction and to form a rational judgment of their 

 action. 



