ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



797 



Fig. 202 



axis of the objective. The prism is inclined on its axis of movement so as 

 to reflect the light in a direction making an angle of SO'' with the horizon. 



There are two tubes each with 

 an eye-piece inclined about 60^ 

 to the vertical, and which can be 

 placed opjDosite each other in the 

 same vertical plane or in two 

 planes at right angles. If the 

 Microscope is intended for three 

 persons there is a middle tube 

 with two lateral ones at right 

 angles with it. 



All the tubes except one have 

 an arrangement for focusing by 

 the eye-piece, so that each ob- 

 server may adjust the instrument 

 to his own sight once for all. 



The possible defect of cen- 

 tering of the objectives, in con- 

 sequence of which the image fails 

 to occupy the same situation in 

 the field of the different eye- 

 pieces, is remedied by allowing 

 the inclination of the tubes to be 



1887. 



