136 THE AMERICAN MONTHLY [May, 



as often it fails just at the very instant it is most needed. Only 

 a few dtiys of this light were available for the nicest photos. 

 They come usually after a long storm to thoroughly clear the 

 atmosphere. The haze of other apparently clear days shows on 

 the positive plate. 1 learned how to determine the presence of 

 this haze by unaided ocular observation. Probubly California 

 is the best place for sun light. 



5. Microscope Stands. — The following were used : 



(a) Tolles B. stand with first class stage R. R. friction move 

 ment and with a draw tube expressly made by Mr. Tolles lor 

 this use. 



(b) Tolles student stand. 



(c) Tolles clinical stand. 



(d) Tolles objectives. 



1. 2d class 1 inch. 



2. 4 system 1st class, 1-lOth inch. 



3. 3 " " " l-16th inch. 



4. 3 " " " l-50th inch. 



5. 4 " " " l-75th inch. 

 No oculars were employed. 



When the B. stand was used it was placed directly on the 

 base board in the center. The tube was placed in a horizontal 

 position. The draw tube was removed and the open end of the 

 special draw tube projected into the empty nose of the camera. 

 By winding a common black shawl about them, extraneous 

 light was cut off. The same shawl answered for a ved over the 

 observer's head while he was looking at the picture ujjon the 

 ground glass plate. 



Tiie student's stand was mounted on a base fastened yet 

 movable, as has been described and used the same as the B. 

 stand. 



The Clinical Stand was used by having black walnut 10 

 x5xl mounted on a small base, which in its turn was fastened 

 to and movable in the 55 inch groove. A hole of the exact size 

 of the microscope tube was bored squarely through the upper 

 end of this block exactly in the line of the 55 inch furrow and 

 opposite the center of the cameral aperture. When the clinical 

 tube was introduced in the right direction it was read}^ for use 

 with the aid of the black shawl above referred to. All the ob- 

 jectives named were us-d with this clinical stand as it wasfound 



