NEGATIVE MAKING 91 



more inches in length and a lens of not over 

 five inches focus, we shall have quite plain 

 sailing. Suppose the object to be the wing of 

 a butterfly from one to two inches in length, 

 mounted on a glass slip with Canada balsam, 

 rendering it quite transparent. A piece of 

 thick cardboard with an opening in its center 

 slightly larger than the object is attached to 

 the front board of the platform by means of 

 the spring clips already named, and the object 

 slide secured to it by same means. If day- 

 light is to be our radiant, the platform carry- 

 ing camera must now be placed upon a table 

 before a window, with its front facing the 

 light; and the window should be darkened in 

 such manner that none can enter save that 

 which passes through the object or specimen. 

 If this is not practicable, another means of 

 preventing extraneous light from entering the 

 lens must be devised, and will be explained 

 presently. The camera is now to be attached 

 to the sliding board and advanced until the 

 lens is within a few inches of the object, which 

 must be moved about on its cardboard sup- 

 port until seen squarely in center of focusing 

 screen. If not amplified sufficiently, the lens 

 must be carried closer to it and the bellows 

 extended further away, the amplification being 



