PKOCEEDINGS OF THE SOCIETYr 183 



focus than tliose generally in use, and it was claimed that, as regarded 

 general finish and capability, it would compare favourably in economy of 

 price with any others. 



Mr. T. Charters White read a paper on "Tartar from Teeth of the 

 Stone Age," numerous preparations being exhibited in illustration. 



Mr. Crisp exhibited a cylinder of glass made at Jena, and described by 

 Prof. Exner in the December number of the Journal, p. 1065, Though it 

 had plane ends it acted as a concave lens, the reason being that it was of 

 varying density from the centre to the circumference. It solved some of 

 the questions which had been raised as to the images formed in an insect's 

 eye. Mr, Crisp also explained Prof. Exner's method of preparing similar 

 cylinders from celloidin and gelatin when the effect of convex lenses was 

 obtained. 



Prof. Bell said that in the interests of the particular branch of science 

 to which he was devoted, he might mention that a little knowledge of 

 histology by certain observers would have shown that the cornea was quite 

 flat in the case of the crayfish, which had nevertheless managed to see very 

 well for a good many years. 



Mr. Crisp directed the attention of the meeting to enlargements on the 

 blackboard of the figures of enormous Microscopes in Schott's ' Magia 

 Naturalis/ 1657. These had long puzzled microscopists, who were at a 

 loss to understand what could be the object of making Microscopes of the 

 large size which was indicated by the comparison with the observers repre- 

 sented as looking through them. Having found in an old book sent to him 

 by Prof. Abbe — Traber's ' Nervus Opticus,' 1690 — what were undoubtedly 

 meant for drawings of the same Microscopes, the mystery was solved ; for 

 if Schott's figures of whole-length men were rubbed out and single eyes 

 were substituted for them, as Traber did in his drawings, the scale of the 

 Microscope represented was of course strikingly altered, and it was seen 

 that they were small hand Microscopes after all. Schott's draughtsman 

 probably had too much of an artistic eye. [Supra, p. 148.) 



Mr. J. B. Medland exhibited and described his new portable cabinet 

 for microscopic slides, in which twelve dozen slides were packed in a space 

 11 in. X 5 in. X 3^ in. (Supra, p. 173.) 



The President thought this was a very simple and practical mode of 

 making a compact cabinet, which would commend itself at once to all who 

 examined it. 



Mr. Crisp exhibited Stein's Electric Microscope. (See this Journal, 

 1885, p. 303). 



Mr. A. W. Bennett gave a resume of his paper " On Fresh-water Algje 

 (including Chlorophyllaceous Protophyta) of North Cornwall," with de- 

 scriptions of six new species, illustrated by coloured diagrams. {Supra, 

 p. 8.) 



The President said they must all feel indebted to Mr. Bennett for his 

 very interesting communication, and they could not fail to note how very 

 much pleasure there must have been added to a holiday in the case of one 

 who had made himself so thoroughly master of this subject. He thought 

 this paper was full of encouragement to others, because every young student 



