ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



609 



SO that it will swing in a plane lying in tlie axes of the two tubes, 

 and when it is swung down into the position shown in full lines in 

 the drawings the prism intercepts one-half of the rays passing 

 through the objective and diverts them to the auxiliary tube. When 



the Microscope is used for monocular vision, the prism is turned out 

 of the field, as indicated by dotted lines in fig. 90. 



Having thus described my invention, what I claim as new, and 

 desire to secure by letters patent, is — 



1. In a binocular Microscope, a swinging prism-holder adapted 

 to support the prism within the body of the Microscope either in or 

 out of the field of vision, as herein specified. 



2. The combination, with the doubly reflecting prism of a bino- 

 cular Microscope, of a prism-supporting arm and spindle attached 

 thereto, and extending outward through the Microscope-body, as 

 described. 



3. The combination, in a binocular Microscope, of the prism C, 

 prism-holder B, spindle D, provided with the stop-pin /, and the 

 slotted sleeve E, as herein specified." 



Sohncke's Microscope for Observing Newton's Rings.* — This 

 instrument (fig. 92) is a device of Dr. L. Sohncke for examining 

 Newton's rings, and it is claimed that it fulfils all the conditions in 

 regard to variety of movements (and their measurement) necessary in 

 such an instrument. 



The microscope-tube (provided with cross threads and magnifying 

 20 to 25 times) slides in a short socket H, the former having a scale 

 in half-millimetres (with a nonius on H) for allowing the exact 

 position to be read off". The socket, with the Microscope, can be 

 turned on a horizontal axis, fixed in the front part of two brass 



♦ Zeitichr. f. lnhlrMmcuteiik.. i. (1881) pp. 55-8 (i fig.). 



