THE MICROSCOPE. 195 



thread; the name and description of this crew was not known. The 

 front of the objective is ground down to a conical shape. For 

 ordinary use this front is covered with a brass cap, having an apera- 

 ture on the centre to allow the conical end of the objective to pass 

 through. The cap can be removed when it is described to use the 

 objective for the examination of opaque objects. On removal of 

 the cap the conical sides of the lens are seen to be covered with* 

 some sort of black varnish to prevent the passage of outside light. 

 A lieberkuhn is furnished with the glass which can be screwed on in 

 place of the cap while examining opaque objects. The speaker had 

 not had the glass in his hands long enough to become perfectly ac- 

 quainted with all its qualities; it certainly is a good one, however. It 

 resolves angulatum very satisfactory and bears eye-pieces extremely 

 well, working admirably on anatomical structures. 



The lieberkuhn seems to be a valuable addition for some sorts of 

 study as it brings out surface markings with unusal clearness, even in 

 transparent objects. Mr. E. B. Stuart exhibited a Hitchcock lamp 

 which he stated commended itself to the use of microscopists. No 

 chimney is required, it being a blast lamp, the flame of which is 

 fanned by a passage of air from the bottom to the top of the lamp, 

 driven by a noiseless clockwork. The oil well is entirely separate 

 from the outside part of the lamp, and is kept cool by the cold blast 

 of air constantly surrounding it. It gives a light of about a six- 

 foot gas burner and the flame is steady and more free from flicker 

 than gas or the ordinary carbon burner. He also showed under the 

 microscope specimens of the gelatin-bromide plate for photographic 

 work, that had been submitted by a photographer as imperfect. An 

 inspection under the microscope showed three kinds of spots. 

 One, caused by dust particles which had settled on the gelatine 

 while still soft, and as the emulsion hardened, became firmly fixed 

 on the plate. The second kind of spots were caused by, apparently, 

 the solvent action of some substance on the fibre as it could be seen 

 to be less dense at those points, while the third were thicker and 

 evidently caused by carelessly spattering the emulsion on partially 

 dried plates. 



The meeting was then declared informal. 



Wm. Hoskins, Secretary. 



