CORRESPONDENCE. 97 



Mr. Ee^iel (not Ke»el) Keith. 



To the Editor of the ' Monthly Microscopiccd Journal.^ 



War Department, Surgeox-General's Office, 

 Dr. H. Lawson. Washington, D.C, June 17, 1873. 



Sir, — In my article on the " Aperture of Object-glasses " in the 

 June number, my friend Mr. Reuel Keith, of Georgetown, appears 

 as Kenel Keith. I suppose my MS. was not sufficiently plain, but beg 

 that this correction may be made in your next. 



Very respectfully yours, 



J. J. Woodward, 



U. S. Anntj. 



Mr. Tolles' Objective.* 



War Department, Surgeon-General's Office, 

 De. Henry Lawson. Washington, D.C, May 19, 187;5. 



Dear Sir, — Since sending my paper on " Angular Aperture," Mr. 

 Tolles has sent me the yV*^ measured by Mr. Wenham. (See 

 ' Monthly Microscopical Journal,' January, 1873, p. 29.) Measured 

 by the method mentioned in my paper, I get a balsam angle of 70° at 

 the open point, and 84° when the lenses are closed to the point of maxi- 

 mum angle, which is reached some time before the screw collar is fully 

 closed. Unlike Mr. Wenham I find this glass performs admirably at 

 the point of maximum angle provided the covering glass is thick enough. 

 I tested it on Grammatophora suhtilissima in balsam under a cover y^^ih. 

 of an inch thick, and obtained what I am obliged to call admirable 

 definition. My friend Mr. Wenham must surely have used too thin a 

 cover for the position of maximum angle, or he could not have arrived 

 at the conclusions expressed in his note. 



I have the honour to be, very respectfully. 

 Tour obedient servant, 



J. J. Woodward, 



Assist tnt-Surgeon U.S.A. 



Inexperienced Artists v. Experienced Ones. 



To the Editor of the ^Monthly Microscopical Jouriicd.'' 



78, King William Street, E..C., July 3, 1873. 

 Sir, — In the current nmnber of the Journal, in Dr. Pigott's jiaper 

 on " High-power Definition," page 21, the following sentence ajipears : 

 " The drawing then taken by a lady of talent, unaccustomed to the 

 microscope, was everything I could desire." This idea has been intro- 

 duced repeatedly by the author, both in his written and spoken com- 

 munications ; and as the following quotation appears apposite, I 

 venture to bespeak attention to it : — 



* This letter was received about the 8rd of June, and should have appeared 

 in tlie Jidy number of this Journal had we thought for a moment that Col. Wood- 

 ward intended it for publication. We have since heard from Col. Woodward, in 

 answer to a communication of our own, who expresses his surprise at its absence 

 from the July number. We therefore, with many apologies, insert it in the present 

 Journal. 



