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PROCEEDINGS OP THE SOCIETY. 
Meeting op 16 th April, 1890, at 20, Hanover Square, W., 
THE President (Dr. C. T. Hudson, F.R.S.), in the Chair. 
The Minutes of the meeting of 19th March last were read and 
confirmed, and were signed by the President. 
The List of Donations (exclusive of exchanges and reprints) received 
since the last meeting was submitted, and the thanks of the Society given 
to the donors. 
From 
Lee, A. B., The Microtomist’s Vade-mecum. 2nd edition, ix. 
and 413 pp. (8vo, London, 1890) The Author. 
Spiral ruling on glass Mr. P. Braham. 
Photomicrographs of Eupodiscus Rogersii, Isthmia nervosa, Navicula 
aspera, and N. Burrandii Mr. Thomas Comber, 
Mr. J. Mayall, jun., called attention (1) to the new edition of the 
‘ Microtomist’s Vade-mecum,’ by Mr. A. B. Lee ; (2) to a spiral ruling 
on glass, sent by Mr. Philip Braham, of Bath, which was curious as 
having been produced in an ordinary lathe, the diamond point being 
adjusted on the slide-rest ; (3) to a series of four photomicrographs of 
diatoms, sent by Mr. Thomas Comber, which would be found on 
examination to be of special excellence. The magnifying power was 
about 1000 diameters, and Mr. Comber evidently possessed first-rate 
appliances, and used them with much skill. Mr. Mayall thought these 
photomicrographs of particular interest from the fact that they were 
produced with sunlight, by which the maximum resolving power of the 
objective was obtained. He understood also that Mr. Comber employed 
monochromatic illumination. It was matter of regret that so few 
English microscopists used sunlight in their photomicrographic work. 
The climate was somewhat unfavourable ; but yet there were occasional 
hours of sunshine that ought to be usefully employed in that direction. 
Artificial light was probably more easily manipulated ; but still there 
remained the fact, long ago demonstrated by the late Dr. J. J. Wood- 
ward, of Washington, that sunlight gave the most perfect results. 
Mr. E. M. Nelson said Mr. Comber had communicated with him on 
several occasions with regard to his apparatus and the methods employed 
by him in producing these photographs. His solar apparatus was of 
the most perfect description, at the same time it was simple, and his 
results showed a high advance upon anything of the kind previously 
done. 
Mr. Mayall referred to an improved form of fine-adjustment con- 
structed and exhibited by Messrs. Powell and Lealand, for the production 
of which he was himself chiefly responsible. 
Dr. Dallinger said he had not yet had an opportunity of examining 
this new fine-adjustment; but he was quite satisfied that the more 
