158 



THE MICROSCOPE. 



the stage-plate, after the maimer of Oberhauser's micro- 

 scopes. An index L is affixed opposite the graduated head 

 k. The stage and clamp slides vertically on h ; and by 

 sliding this up or down, and the glass object-slide hori- 

 zontally, the requisite amount of movement is obtained to 

 bring the object into the field. The object being brought 

 into view, the image is roughly adjusted on the focussing- 

 glass by sliding c on a ; the focussing is completed by aid 

 of the fine adjustments g k, and allowance then made for 

 the amount of non-coincidence between the chemical and 

 visual foci of the object-glass. The difference in each glass 

 employed should be ascertained by experiment in the first 

 instance, and then noted. By employing a finely-ground 

 focussing-glass greased with oil, this arrangement forms an 

 agreeable method of viewing microscopical objects w T ith 

 both eyes, and is less fatiguing. As a very large field is 

 presented to the observer, this arrangement might be 

 advantageously employed for class demonstration. 



Fig. 97. — Highley's PJioto-micrographic Arrangement. 



This arrangement combines the most recent improve- 

 ments of Dr. Maddox, and consists of a lens-carrier with 

 ordinary adjustments; stage with gymbal motions so as 

 to bring any object parallel to the surface of the object- 

 glass ; bright ground illuminator, graduating diaphragm ; 

 and a speculum reflector for giving the light from a 

 single surface. 



