1899] MICROSCOPICAL JOURNAL. 127 



MICROSCOPICAL 4PFARATUS. 



Quekett Club.— The 364th meeting- held Friday, Dec. 16, 

 Dr. John Tatham, president. After the usual formal busi- 

 ness, Messrs. Swift exhibited a microscope on their four- 

 legged tripod model, which, except wearing- surfaces and 

 screws, was entirely constructed of aluminium. Also an 

 objective, said to be the first with the whole mount in 

 aluminium. It was very light and most beautifully made. 

 The aluminium objectives are likely to spare the strain on 

 the fine adjustment, in some forms at least. An advantage 

 of the lighter metal is for the stands of traveling micro- 

 scopes. It is more costly to make than the usual brass and 

 gunmetal. Mr. H. Schroeder gave a detailed description 

 of a new projection microscope, which could be used for 

 exhibiting on the screen all kinds of objects, prepared or 

 recent, including crystalization under polarized light. He 

 explained the construction of the peculiar form of electric 

 lamp used in conjunction with the projection apparatus, in 

 which the upper carbon is in the form of a revolving disc 

 and the lower a thin finely-pointed rod. Mr. Nelson had 

 never seen a projection microscope capable of giving a 

 well-defined bright image on the screen, visible at any dis- 

 tance, with powers beyond a 2 in. or 1 in. The want of 

 light with the higher powers was a serious drawback to 

 projectors. An interesting paper was read by Mr. Nelson 

 entitled : "On the Structure of Nodules in Pleurosigma 

 and Climacosphenia," illustrated by photo-diagrams with 

 the lantern. He thought a comparison of the tubes in the 

 raphe and their junction by a minute canal in the central 

 nodule, from specimens found in the Nottingham Deposit 

 with recent Pleurosigmas,showed some evidence of evolu- 

 tion. Optically these minute tubes were at the limit of visi- 

 bility and excellent tests of definition in objectives. 



MICROSCOPICAL MANIPULATION. 



Varnish. — The different colored varnishes can be very 

 easily prepared by coarsely powdering sealing-wax of the 



