296 PROJECTION MICROSCOPES ON THE MARKET [Ctf. IX 



FIG. 161. THUMB SCREWS AND THUMB NUTS. 



(From the Catalogue of the Hartford Screw Company). 



Thumb screws and thumb nuts are necessary if one is to construct home- 

 made apparatus. 



PROJECTION MICROSCOPES OBTAINABLE IN THE OPEX MARKET 



433. The projection microscope so far considered in this 

 chapter was designed to give the range needed for modern micro- 

 projection in a biologic or other laboratory, that is, for use with 

 specimens slightly smaller than lantern slides (50 to 65 mm. in 

 diameter) to those of i mm. or less (fig. 121, 147). 



