1892 



Journal of Applied Microscopy 



The Technique of Biological Projection and Anesthesia of 



Animals. 



Copyrighted. 



V. PROJECTION MICROSCOPES USING ELECTRIC ARC OR OXYHYDROGEN 



LIGHT. 



That the projection microscope is destined to fill an increasingly large and 

 important place in class and lecture room work in colleges and secondary schools 

 and in popular educational lectures, seems evident. Its general utility depends 

 upon the success with which three practical problems are solved. First, a light 

 of intense brilliancy must be produced and kept in the optical axis of the instru- 

 ment. Second, the system of condensers must collect the largest possible per- 

 centage of light rays from the luminous point and deliver them at the proper 

 angle of convergence for each of the objectives to be used. Third, the appara- 

 tus must not be too cumbersome or complicated or too expensive for ordinary 



Fig. 4. — Projection Microscope with 'JU° Hand-feed Arc Lamp. The body is 

 tilted up to expose the lamp and the electrical connections. 



use. The instrument illustrated in this article is an attempt at a solution of 

 these problems. The engraving shows the body rotated upward on the top of 

 the plate, and held in position by a slender support so as to give a clear view of 

 the 9U° arc lamp and electrical connections. 



The base board is cut away under the lamp so as to permit the use of long 

 vertical carbons. At the rear end and right side of the board is placed the 

 switch in the most convenient position for use. On the opposite side of the board 

 is the fuse-block. At the right of the fuse-block, as seen in the illustration, are 

 two binding-posts connected with the fuse-block by two twisted flexible wire 



