ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 



809 



Fig. 149. 



light. Upon E is a scale which gives the distance of the objective from 



the focusing plate. 



The advantages claimed for the instrument are " the firm stand resting 



on three points, and the attach- 

 ment of the whole (illuminating 

 apparatus and camera) to a com- 

 mon stand," " the Microscope, 

 illuminating apparatus, and 

 front part of the camera being 

 capable of being brought to 

 dilierent distances from the 

 focusing plate without the posi- 

 tion of the separate parts to each 

 other being in any way changed." 



Neuhauss's Focusing Ar- 

 rangement. — Dr. E. Neuhauss 

 uses for the camera described 

 ante, p. 294, the mechanism 

 shown in fig. 150. 



Fig. 150. 



A piece of watch-spring is bent as shown in the figure, and is 

 secured to a pin attached to a plate. The Microscope being horizontal, 

 the plate is placed vertically with the ends of the watch-spring engaging 

 in the milling of the micrometer-screw of the fine- adjustment. To the 

 sides of the bottom of the plate cords are attached, which pass over hori- 

 zontal pulleys on the right and left of the Microscope and are fastened 

 to a wooden rod at the end of the camera. By pulling the one cord or 

 the other the fine-adjustment screw is turned to the left or right. 



"In this way" (see p. 294) "the fine-adjustment is made without 

 any inconvenient connecting rods, and can be effected directly by one 

 hand, while the other is engaged with the focusing lens." The motion 

 obtained by the action of the clamp on the micrometer-screw is, it is 

 claimed, quite fine enough to secure the complete sharpness of the 

 image. 



Drawings v. Photographs.— Screen for the Abbe Camera Lucida.* 



— At the present time, when to almost every Microscope a photographic 

 camera is being attached, and when photomicrographs, of every degree of 

 merit, are being produced on all sides, it may be well, Dr. Gr. A. Piersol 

 considers, to weigh the respective values of the pencil and sunbeam as 



* Amer. MoQ. Micr. Jom-n., ix. (18S8) pp. 103-4. 



