108 



THE MICROSCOPE. 



the small air-pump, fig. 74, is very serviceable. This is 

 made by Baker, of Holborn, at a moderate price. The 

 mode of using it, after the object has been placed under 

 the bell-glass c, is by drawing up and pushing down the 

 handle B, to pump out the air from around the object to be 

 secured and preserved. By turning the small screw at D, 

 you let in sufficient air to remove the bell-glass : it is better 

 to allow the object to remain under for several hours until 

 the cement around the edge of the glass cover becomes 

 perfectly dried and secure ; then, upon exposure to the 

 external air, it will no longer affect it. It will be also 

 found useful in withdrawing the air from the cells of 

 woods. The pump itself, A, when unscrewed, can be used 

 as an injecting syringe for fine anatomical injections. 



JPig. 75. Steam Bath, by Mr. Gibbons. 



The accompanying is a drawing of a simple form of 

 Steam Bath, for mounting, and other uses. A is a conical 

 tin boiler, five inches in diameter, just large enough to 

 enable the operator to vaporize a small quantity of water 

 when placed over a lamp. B is a cage of perforated 

 metal, made to hold one or more objects, which should fit 

 tightly at the collar D ; into this a small escape-pipe is 

 stopped with cork or luting, so that the steam shall pass 

 around the object, and escape through it. 



This will also serve for the immersion of objects, such 

 as parts of insects, &c., in turpentine, previous to mount- 

 ing them in balsam. The plan recommended is, to immerse 



