A WORKING MICROSCOPE. 39 



manner as has been already shown in Fig. n. There are 

 coarse and fine adjustments, a diaphragm in the thickness 

 of the stage, plane and concave mirrors, the whole costing 

 the author the moderate sum of three guineas and a half. 



With this form one is not bound to bad or medium eye- 

 pieces and objectives ; they can be bought separately and 

 selected. We should like to see some enterprising manu- 

 facturer making the instrument as shown in Fig. 24, and 

 selling it for six guineas with an A eye-piece and a good 

 inch objective, or without eye-piece and objective for 3/. los. 

 The details of this instrument are as follow: When 

 standing vertically and closed down, the top of the eye- 

 piece is ii inches from the table, the collar in which the 

 body slides being 3 inches in length, and lined with velvet. 

 The body is 5 inches in length, and the draw-tube 4J inches, 

 with an outside diameter of 1*3 inches ; the stage is 

 3 7 inches from the table, and has a diameter of 3 inches ; 

 the mirrors are 2*2 inches in diameter, and the fine ad- 

 justment raises or depresses the entire body T -J-g- of 

 an inch for each complete revolution. The stage is less 

 than of an inch in thickness. The author has found 

 this a very convenient instrument for photomicrography 

 and for general microscopical work. The substage fitting 

 will take all accessories made to the usual I J-inch gauge. 



It is greatly to be deplored that there exists no universal 

 gauge for eye-pieces and substage fittings, is it too much 

 to ask the Council of the Royal Microscopical Society to 

 take the matter in hand ? 



