330 



THE MICROSCOPES OF 1894. 



Figs. 5 and 6 show the two simplest forms of this class of 

 microscope ; Fig. 5 being a rigid stand with a sliding coarse 

 adjustment, the fine adjustment being by micrometer screw. The 

 body tube is of the Continental tube-length (160 mm.), extending 

 by means of the draw-tube to 200 mm. (8 inches). The eye- 

 pieces are also of the Continental size. The makers call especial 

 attention to the manner in which the fine adjustment is capped, 

 thus preserving it from disturbance or injury by dust. Fig. 6 shows 

 the stand inclined ; it will be seen that the instrument is provided 

 with a knee-joint below the stage. The pillar is so arranged that it 

 can be rotated on its base, reversing the position of the stand, and 

 thus securing the stability of the instrument. When the instru- 

 ment is used vertically, it will be seen that the centre of gravity is 

 so placed that there is an equal steadiness in every direction. 



Fig. 7. 



Messrs. Ross have adapted the ring foot to a petrological 

 microscope (Fig. 7). This stand has a revolving circular stage 

 graded to 360°. The analyser, which can be drawn out when not 

 needed, is fitted to the lower end of the body-tube, in which there 



