LETTERS TO THE EDITOR. 281 


mind must be given up, and such subjects are usually styled dry, 
especially by the younger members. There were no doubt many 
present who were capable of entering into the discussion, but cer- 
tainly some of the statements and explanations of Mr. Miles 
completely “took the wind out of their sails,” and so they preferred 
to sit still and say nothing, the more especially as the essayist had 
given the paper a very decided personal turn. It is a pity that 
scientific societies should not insist upon eliminating the personal 
element from their papers. 
I hope, sir, you will allow me to suggest to the reader of the 
paper in question the propriety of revising his information on the 
spectrum. How astonished he would be to see a photograph taken 
through red glass! But, according to him, photography is possible 
in the dark! I fully expected the paper would be a digest of all 
those beautiful communications which have appeared during the 
past two years in the Journal of the Microscopical Society, but, to 
my disappointment, it contained only such statements as these, 
without any attempt at proof :— 
“Consequently the visual angle under which we see an object is 
always in proportion to its amplification.” 
“My contention to-night is” * * “that in the computation or 
formulating of objectives a just proportion of power and aperture 
should always be maintained.” 
“ Now the highest attainable aperture is soon reached.” 
“T could not for the life of me recollect what merits in particular 
were ascribed to powers of wide aperture.” 
“This of course will give increased penetration.” 
“It scarcely needs demonstrating that an inferior image must be 
the result.” 
Now, sir, I strongly object to such assumptions as these without 
proof, and I must argue that Mr. Miles’ paper has been a most 
disappointing one, for it is when looked into carefully a sharp attack 
without argument, or in the words of the chairman, “‘it is quite 
certain some of the remarks are a little hard upon Mr. Davis.” 
I hope, sir, you will not let the matter rest. 
I am, etc., 
PHOTO. 
. Str, 
Being present at the last meeting of the Manchester Microscopi- 
cal Society when Mr. Miles attempted to explain what “aperture” 
was, I was surprised to hear him declare that 180° or an aperture 
of 1.0 was impossible of attainment. Can it be true that the papers 
read before the R. M. S. can have produced such little result? but 
what shall be said of one who endeavours to enlighten his brother — 

a 

