PROCEEDINGS OF SOCIETIES. 139 



Bolgiau stones. These specimeus were from North Wales, and for a 

 while were in use in this country. 



In 1824 he invented his first lever stage-movement for the micro- 

 scope for following the movements of live objects, for which he 

 received the large silver medal of the Society of Arts. This was 

 subsequently considerably improved in effecting the object in view 

 by means of a single lever, and for the latter he received the gold 

 Isis medal of that society ; and it was considered to be the best lever 

 movement of the day. 



In 1826 he produced a plano-convex diamond lens, which jios- 

 sesses one advantage over lenses of glass in having about double the 

 magnifying power with the same radius. This lens was exhibited at 

 the Eoyal Institution in February, 1826, on the occasion of the third 

 Friday Evening Lecture. But the diamond labours under the disad- 

 vantage of having no medium of higher refrangibility, by means of 

 which its aberrations may be corrected ; and the construction of 

 diamond lenses was not piu'sued further, as the doublets of WoUaston, 

 and subsequently achromatic and aplanatic combinations, altogether 

 suj)erseded the use of single lenses in the construction of compound 

 microscopes. It may here be remarked that the diamond, as be- 

 longing to the regular system of crystals, and therefore possessing no 

 double refraction, is the only gem that stood any chance of useful 

 application ; other gems having high refractive indices belong to 

 crystalline systems in which double refraction is invariably present, 

 a property wliich must obviously interfere with optical definition. 



C. Varley was one of those microscopists who met and founded 

 this ■ Society on September 3, 1839. In the second volume of the 

 Society's Transactions will be found an elaborate description of the 

 growth and development of the " Chara vulgaris." One characteristic 

 of this plant discovered by him was the emission of certain ciliated 

 bodies (to which he gives no name, but which are now known as 

 Antherozoids), which possess spontaneous motion for about two 

 hours, and closely resemble the spermatozoa of animals. Various 

 other papers on this and kindred subjects will be found in the 

 Journal of this Society, and in that of the Society of Ai-ts, relating to 

 the structure of this plant, and to that of the Nitella flexilis, N. trans- 

 lucens, and N. hyalina. The plates in these papers were accurately 

 drawn from the living plants by his " Graphic Microscope." He also 

 contributed papers on the fungoid disease of the common house-fly, of 

 the nature of which he was the discoverer. 



' Mr. Varley preserved his intellect to the last, and was profession- 

 ally occupied three weeks before his decease, which occurred on 

 October 2, 1873, and consequently in his ninety-second year, after 

 having been in a state of coma for twelve hours. 



John Augustus Tulk, Esq., of Addlestone, Surrey, was elected in 

 January, 1860, and died in December, 1873, aged fifty-nine. Although 

 unable from the locality of his residence to attend the meetings of 

 the Society frequently, he was much interested in microscopical 

 research, having in 1857 become acquainted in Edinburgh with the 

 late Dr. Greville, one of the most painstaking and successful investi- 



