92 



MICROSCOPIC ILLUSTRATIONS. 



on discs in this manner, an additional arm for carrying a 

 small black cup, to be placed behind the object, in lieu 

 of the disc, is extremely convenient. 



Description of the Solid Tripod-stand Achromatic 

 Microscope and Engiscope. This instrument, on its 

 simplest mounting, is represented by the accompanying 

 engraving, fig. 1J. It is in all respects similar to the 

 preceding one, except in its stand. On this account 

 I have placed it in the position in which it is used for 



Fig. 17 



