Scientific Proceedings, Royal Dublin Society. 
Fig. 1 
i 
In Fig. 1. a.a. Is the declination circle. 
6.6. Is the upper A circle, which is stationary, the vernier 
being carried by the polar axis. 
rr. Isa telescope with a right angle prism on end inserted in 
the great telescope tube at one side, parallel to its axis. 
