NEGATIVE MAKING 53 



inserted into its front opening and the en- 

 trance of all extraneous light excluded by 

 wrapping a piece of some dark fabric about 

 the junction, or in any other manner one may 

 decide upon; in this case a focusing cloth of 

 cotton-velvet is used. We now find that the 

 whole of our specimen is included within the 

 circle of light seen on the focusing screen. 

 The illuminated disc, however, is somewhat 

 contracted and shows a very bright spot of 

 light on one portion of its surface which inter- 

 feres with the definition of the image and 

 threatens to spoil the negative unless removed. 

 This is readily done when its origin is found 

 to be reflection from the too bright interior 

 surface of the tube or compound body of 

 microscope. A tube of velvet or dead black 

 paper inserted within the body effectually 

 cures this " flare spot" trouble, but unfortu- 

 nately contracts the already too small diameter 

 of the tube, a defect held in common by most 

 of the modern students' form of microscopes. 

 In the Spencer stand we are using, this defect 

 has been largely remedied by the employment 

 of an outer body of unusually large diameter, 

 from which the sliding tube may be entirely 

 removed, leaving one of a very excellent size 

 for photographing an image projected by 



