378 THE AMERICAN BIONTHLY [Dec. 



the book, or print to be copied is fastened. The lighting, 

 focusing and all subsequent details, are of course famil- 

 iar to every photographer, I cannot even hint at them 

 here, save to suggest that if the copy is for lantern pur- 

 poses, it will be well to make it at once of the proper 

 size to permit printing by contact, thus effecting a con- 

 siderable saving of time. 



Negatives of microscopic objects are generally made 

 considerably larger than the dimensions of a lantern 

 slide, though in some cases as a minute diatom for in- 

 stance, they are much too small. In either case the lan- 

 tern slide must be made by reduction or enlargement as 

 necessary. For these purposes the camera is arranged 

 precisely as for copying, except that its front end must 

 face the window and be close to the latter. A large 

 sheet of white paper is to be laid upon the platform as a 

 reflector and on this the stand used in copying, and car- 

 rying a frame containing the negative, must be placed. 

 A focusing cloth or other covering is then spread over 

 the space between the frame and camera, so that no light 

 may enter the lens save that which passes through the 

 negative. The camera is then moved to or fro upon its 

 ways, until the image projected upon the screen is of the 

 proper dimensions when it is to be fastened in that po- 

 sition, the focus sharpened by moving the bellows and 

 the balance of the necessary work of exposure and devel- 

 opment done in the manner familiar to all who have 

 mastered the simple mysteries of photographic manipu- 

 lations. 



The accompanying cuts fully illustrate the various 

 methods of usinor the instrument. 



We are prepared to furnish blank applications for mem- 

 bership in the American Microscopical Society. 



