( 529 ) 



PROCEEDINGS OF THE SOCIETY. 



Meeting of 13th April, 1887, at King's College, Strand, W.C, 

 THE President (the Key. Dr, Dallinger, F.R.S.) in the Chair. 



The Minutes of the meeting of 9tli 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 



Slides (13) of Diatomacese Mr. B. W. Thmnas. 



Vhoiova.icT[Ogra,^\i& oi Floscularia, Melicerta, sindi Stephanoceros .. .. Mr. J. B. Robinson. 

 Photomicrographs of Snow Crystals Mr. A, W. Waters. 



Mr. B. W. Thomas's letter was read in reference to the thirteen slides of 

 diatomacese, in which he suggested the necessity of having standard Malt- 

 wood finders. 



Mr. Beck said there had been spurious imitations of Maltwood finders, 

 so that it was impossible to guarantee the quality of all that were in exis- 

 tence. All the genuine ones, however, agreed with one another to within 

 1/1000 in. Mr. Maltwood originally asked them to carry out his plan, and 

 they had a glass plate engraved, and all the finders they had sent out had 

 been photographed from this. No doubt some enterprising American had 

 endeavoured to make Maltwood's finders so as to offer them for a few pence 

 less than the genuine ones. All the genuine Maltwood finders were made 

 to the same standard, and there was no practical difficulty in insuring their 

 correctness. 



Photomicrographs of living rotifera {Floscularia, Melicerta, and Stepha- 

 noceros), by Mr. J. B. Robinson, were exhibited ; also photomicrographs of 

 snow crystals taken at Davos Dorfli, by Mr. A. W. Waters, showing some 

 remarkable forms. 



Mr. T. C. "White exhibited a series of photomicrographs which he had 

 recently taken, showing the results of the method of cutting off some of the 

 superfluous light by means of a sliding diaphragm, so as to be able to admit 

 just enough to bring out the detail and nothing more. The specimens 

 shown were printed on Eastman's bromide paper, instead of silver paper, 

 which he found brought out the character of the detail very much better. 



The President was sure it would be interesting to all to note the improve- 

 ments shown in these productions by Mr. White. The photomicrographs 

 were certainly remarkably clear, and showed a distinct advance upon any- 

 thing he had seen before. 



Mr. F. R. Cheshire said that the small bottle which he held in his hand 

 contained an object unmounted, which was very rarely seen, because ex- 



