419 



PROCEEDINGS OF THE SOCIETY. 



MEETING 



Held on the 19th April, 1911, at 20 Hanover Square, W., 

 H. G-. Plbimer, Esq., F.R.S., etc., President, in the Chair. 



The Minutes of the Meeting of March 15th were read and con- 

 firmed, and were signed bv the President. 



The following Donations received since the last Meeting were an- 

 nounced, and the thanks of the Society voted to the donors : — 



From 



J. Arthur Thomson and J. J. Simpson, Alcyonarians of the 1 The Trustees of the 



Indian Ocean. Part II. (4to, Calcutta, 1909) j Indian Museum. 



\ 1 /V T T 7 l\fo )'} n nil 

 Slide of AulacodAscus superbus in Styrax > * ' T] ' 



Mr. Conrad Beck exhibited a new Microscope, which he said was of 

 very much the same type as other instruments, except that it had a limb 

 of such a shape as to form a handle. The slow motion, worked by a 

 lever inside the body of the Microscope, was entirely in front of the 

 limb, so that in lifting the instrument no alteration in the adjustments 

 was likely to occur. The other adjustments were the same as were 

 usually found in that particular type of Microscope. 



The thanks of the Society were accorded to Mr. Conrad Beck for his 

 communication. 



Mr. Spitta gave a demonstration on "Low-Power Photomicrography, 

 with special relation to a colouring method for tinting lantern slides." 

 In his preliminary remarks, Mr. Spitta said that the subject of photo- 

 micrography might be divided into three different sections — namely, 

 high power, medium power, and low power work. With high power 

 photography, an objective having a focal length of, say a twelfth or 

 thereabouts, was employed ; in medium work one of, say a quarter or a 

 sixth was used ; but with low power, an inch, or one of still greater 

 focal length, was usually selected. In that branch of low power work 

 where the objective was of longer focal length than an inch, it was 

 customary not to employ a Microscope at all, the objective being at- 

 tached to an ordinary camera. In olden days the selection of objec- 

 tives for this particular branch of low power work was a source of no 

 little difficulty, for they were mostly of the ordinary photographic 

 variety that did not work at a greater aperture than J/8, and their 

 corrections were such that they did not produce very good images, the 



