OBSERVING WITH AND MANAGING ENGISCOPE. 207 



lens, &c. so as to prevent any false light from getting 

 into the object-glass, and also to furnish a black ground. 



Remove the bottom of the black box, 'p, and fix the 

 condenser, n, in such a position, by means of its tight- 

 ening screw, that its convexity shall be inserted into the 

 bottom of the said black box, which will be found its 

 best position either for day-light or candle-light. The 

 engiscope must then be placed on the tripod-stand 

 mounting. No. 1, and directed against the sky, (the 

 best way, perhaps, of using the cups, with day-light], 

 or it may be used in an horizontal or vertical position, 

 and the light reflected by the oval mirror; but when 

 artificial light is preferred, use the mounting No. 2, 

 and place an Argand lamp about an inch and a half 

 from the condenser, n, taking care that its flame is con- 

 centric with it, and a most intense illumination will be 

 procured, even with powers equal to the l-60th of an 

 inch focus. Cups, when properly managed, give a 

 brighter light than can be procured by any other 

 means. They may be used without the assistance of 

 the condenser, but, of course, in this way give a much 

 more feeble light. 



Please to remember that the condenser under the 

 stage, and that represented attached to the body, are 

 expressly and exclusively devoted to opaque objects. 



8th. Mounting for Dissections, fyc. Dissections are ge- 

 nerally performed on opaque subjects, though it may be 

 sometimes necessary to dissect transparent ones also. 



