422 Rev. W. R. Dawes on an Equatorial. 
tension. The sector and cylinder thus move together wi 
n the same arbor with the cylinder is the wheel,.16 i 
in circumference, in the racked edge of which the driving-ser 
works. This arrangement gives the screw about the same dri 
ing-power as if it acted on the edge of a wheel nearly 40 inches 
in diameter, fixed on the polar axis. 
ave every reason to be satisfied with the going 
out my expectations, founded on the character given by 
Messrs. Bond of the clock-work applied by the same makers 0 ; 
the great Munich equatorial in Harvard Observatory, while! 
been so successfully employed for the purposes of tele 
photography. While the speed of the clock is reg 
vibrations of the half-seconds pendulum, the action 0 
Jum on the wheel-work is rendered smooth and equable b 
For producing a slow motion in right ascension, 
screw is mounted on a brass frame, which, beimg car! 
fine screw under the observer's control, acts as a slippiug1 
through nearly five minutes of time. 
rm clamp, close to the cradle of the telescope, 4 
declination-axis, and is accessible to the observer 
eye-end,.and also during the setting of the declination-¢! 
slow-motion screw acts on an arm extending from the ¢ 
the bottom of the cradle to which the screw is attached. 
To permit the adjustment of the polar-axis to the latitu 
meridian of the place, the upper part of the cast-iron bed 
is made with a groove which receives loosely a projec” 
on the portion bolted down to the pier. The form DOM” 
groove and of the keel being semicircular, the uppeT PO 
moved upon the lower by the stout screw which 1s see? 
drawing, and the polar-axis is thus easily raised to the 
angle. The adjustment to the meridian is performee © 
screws on each side of the groove in the upper piece P 
