184 



THE MICROSCOPE. 



from this surface are reflected down on the object by a 

 plane mirror attached to the object-glass, and on a level 



Fig. 107. Condenser and Table Gas-lamp. 



with the outer surface. By such means the structure of 

 the scale of the Podura, and the different characters of its 

 inner and outer surfaces, are rendered distinctly visible. 



Lamps. It is of the utmost importance, both on account 

 of the injury often done to the eyes, as well as for the per- 

 fection of illumination when artificial light is employed, that 

 its quality should be of the whitest and purest kind. The 

 most useful and economical lamp is Collins' Bockett lamp ; 

 it consists of a good paraffin lamp, reflector, and a 2^ 

 condenser, mounted together on a brass-rod stand, which 

 admits of being raised from 9 to 1 6 inches. The pale -blue 

 chimney supplied with it gives whiteness to the flame, 

 and for all the requirements of the microscopist it is de- 



