1368 



Journal of Applied Microscopy 



HYPO 



rily while the field is being found. Mr. Bausch asked me how I proposed to 

 effect this, and I was forced to reply that I had not the least idea, but must leave 

 it to him. Mr. Patterson, who had charge of the work, came to the rescue with 

 a very ingenious device, which will be described further on. 



It is, however, always best to avoid mechanical focusing, and be able to reach 

 the fine adjustment with one's fingers, if possible, especially for the higher powers. 

 In the B. & L. stands that I had hitherto seen, this appeared to be an impossi- 

 bilitv, except within a very limited range, since the arrangement of the bellows 

 was such that a shorter distance than fourteen inches could not be obtained 

 between the eye-piece of the microscope and the ground glass of the camera. 



Besides this, the front of the camera was always made the same size as the 

 back, i. e., 11 inches square for a i}}2 x8i4 plate, so that the wrist had to be 

 bent round over the front to reach the fine adjustment, thus losing three or four 

 inches of distance for hand focusing. 



Not only is the hand focusing superior in accuray, but it is essential for 

 another reason to be able to get the ground glass close up to the front, since the 

 up-to-date apochromatic lenses will stand very high eye-piecing, with consequent 

 shortening of focus. The higher the eye-piecing the shorter the focus for a 

 o-iven enlargement, as is illustrated by the accompanying photographs, all of 

 which were made with this apparatus. 



It will be noticed from the 

 description and the accompany- 

 ing cut that the disadvantages 

 mentioned have been over- 

 come. With the new apparatus 

 I can bring the ground glass 

 as near as seven inches from 

 the eye-piece, and can focus by 

 hand without any fiexing of the 

 wrist, the total range for hand 

 focusing being about sixteen 

 inches with a Zeiss projection 

 ocular. The choice of a micro- 

 scope stand was narrowed down 

 to a Zeiss photographic and a 

 Bausch & Lomb DD, the latter 

 of which was finally decided 

 upon since the former does not 

 appear to offer any very special 

 advantages, and the fine adjust 

 ment is situated so far forward 

 that two inches in length would 

 be lost for hand focusing. 



Another improvement sug- 



5 I N K 



D E V 



LOAD 



DARK 



ROOM 



PT/ 



O 



BE 



STOOL 



CAM 



STA 



NCH 



E RA 



ND 



Fig. 2. — Plan of Room. 



gested was in making the camera stand entirely of metal. The wooden bed of 

 the old style is liable to warp, and thus throw the rods out of true. 



