J. J. WOODWARD ON PHOTOGRAPHS OF MICROSCOPIC WRITING. 229 



with the coarser bands of Nobert's plate, I took a photograph of 

 the first seven bands of the 19 band plate with 650 diameters, 

 which I also forward herewith. 



This photograph, and that of the blackened writing, were taken 

 on the same day with the same objective, Powell and Lealand's 

 immersion ith, at the same distance, and under identical con- 

 ditions. The photograph of the writing was made first, and is the 

 best of a number of trials. I then inserted the Nobert's plate, not 

 even changing the cover correction, as I should have done to secure 

 the best definition, because this would have changed the power. 

 The picture sent was the result. 



A comparison of the two pictures will render any remarks on the 

 relative delicacy of Mr. Webb's work and that of Nobert un- 

 necessary. It is evident that the point used by the former is very 

 much coarser than that used by the latter. 



The picture of the Prayer, mounted dry, was taken on a sub- 

 sequent occasion, and is iilso the best of a number of trials. It is 

 taken with the same objective as the other pictures, but with a 

 different cover correction, and somewhat greater distance. 



Both the samples sent me by Mr Webb are inscribed on such 

 thick covers that they are seen under a disadvantage, and my 

 highest powers cannot be used on them. The writing is, however, 

 comparatively so coarse that it can hardly be considered as a 

 serious test for high powers. Either plate is easily read with a 

 good half-inch objective and central light. 



I am curious to learn how this writing of Mr. Webb's compares 

 with that of Mr. Peters, described by the late Mr. Farrants in his 

 address as President of the Royal Microscopical Society. He 

 stated that it was executed at the rate of twenty-two Bibles to the 

 inch. I would greatly like to see such a specimen, and give it a 

 photographic trial. 



Will you kindly read this note to the Club, and present the 

 photographs ? I send also a full set of my last photographic 

 analysis of Nobert's plate for the Club, and a package for Mr. 

 Webb, which I beg you to hand him. 

 Very respectfully, 



Your obedient Servant, 



J. J. WOODWARD, 



Assistant Surgeon, U.S.A. 



(Read Jan. 2orcZ, 1874.) 



p 2 



