G-RUBB — On an Improved Equatorial Telescope. 



493 



«cope. If the proportion between the pinion g and its wheel / be 

 the same as that between the pinion c and its wheel d, it is evident 

 that any angular movement of the telescope upon its declination 



axis (which of course causes the pinion g to roll round in the teeth 

 ■of its wheel/) will cause a precisely similar angular movement in 

 the wheel d at the eye-end of the telescope. This wheel d, therefore, 

 becomes the declination circle. 



