208 
CORRESPONDENCE. 
common photographic camera, and photographs taken in the usual 
way. About eleven seconds was stated to he sufficient exposure for 
the purpose. 
Professor Abbe’s new Book on Optical Instruments. — We are 
informed that Professor Abbe intends to give his papers on the 
microscope — one of which appears in print in the present number 
of this Journal — in the form of a complete book “ on the theory of 
optical instruments.” 
CORRESPONDENCE. 
Observations on Mr. Branwell’s Letter. 
To the Editor of the ‘ Monthly Microscopical Journal 
Boston, Mass., U.S.A., August 10, 1875. 
Mr. Editor, — I have been much interested in the proposition by 
Mr. R. Branwell in the August number of this Journal. Some micro- 
scopists may at once accept his dictum that the opinions of certain 
persons named settle at once and for ever a certain disputed point ; 
most others equally as competent may not accept that dictum, and the 
pages of that same number of the Journal afford ample evidence of 
the fact. 
Mr. Branwell says, “ The finest glass ever made would have but a 
limited sale, and probably would be condemned by the public because 
it could not perform on a diatom so well as other known glasses of 
even moderate excellence.” 
I challenge Mr. Branwell’s theory. I claim that the “ finest glass 
ever made ” or yet to be made will perform best on the diatom, and I 
maintain the converse proposition that the glass that will not perform 
best on the diatom is not the best for all other work. These pro- 
positions I am ready to prove by glass that are the best. No opinion 
to the contrary can be of any value unless the parties giving the 
opinion have tried them. 
It is time the humbug was exposed and done with, that glasses fit 
for the study of diatoms are only fit for them. The fact is, the 
diatoms are the best objects in nature for the study of microscope 
objectives. 
Charles Stodder. 
[Mr. Stodder, if not remarkably clear in some of his utterances, is 
at least bold in his expression of opinion. We fear, however, that 
those who have most studied microscopic anatomy will not accept his 
propositions. — Ed. ‘ M. M. J.’J 
