Illuminating Opaque Objects. By J. E. Stead. 



23 



For low-power work, it has been found by long experience that 

 the simple cover-glass reflector is all that is required, but more 

 perfect illumination can be obtained by replacing the plain cover- 

 glass by a silver mirror, so adjusted as to only partly cover the 

 object, as in the Sorby-Beck reflectors. 



For higher powers the reflector is always placed in a slit in the 

 object-glass, and the electric lamp is attached to the object-glass 

 in such a position that, when the current is turned on to the 

 lamp, the object is invariably perfectly illuminated. Fig. 4 will 

 explain the arrangement. 



FIRST POSITION 



(reacj vzmm. 



Fig. 5. 



