Five-feet Equatorial Instrument. 7 
showing how the conical parts of the axis and telescope are 
united, as well as the radial bars which proceed from the axis 
and telescope almost to the border of the circle, and how these 
bars, thin as the tinned plate is, are rendered firm and inflexi- 
ble. It is on this side that the levels would be seen ; one of 
them is parallel to the telescope, the other to the declination 
axis. In fig. 1 , is seen the support of one end of the latter, 
above the polar axis, and nearly half way between the centre 
of the circle and its limb ; here a circular aperture in the drum 
is represented as being quadrisected by a cross. This has, in- 
serted in its centre, a small pivot or cylinder pointed inwards, 
upon which one end of the level is supported, while, on the 
articulated side, a cross and similar pivot support the opposite 
end. Both of the pivots are adjustable by screws, and the 
adjustment being duly performed by them, the horizontality 
of the axis is ascertained in every position of the telescope, 
when directed to the meridian. The other level, which is 
the larger, hangs upon similar adjustable pivots, which ad- 
justment being performed, places the level parallel to the 
line of collimation of the telescope, serving at all times to 
ascertain the due elevation of the polar axis, as well as to 
answer many other useful purposes. 
The clamps and screws for slow motion deserve notice ; 
the former from being unusual, and both from being good. 
Instead of the common mode of clamping upon the circle, in 
this instrument the clamp is made to grasp the axis. There 
is soldered on each axis a ring of brass, the outer edge of 
which is broad and cylindrical. On this fixed ring a mov- 
able one is well fitted, and afterwards cut into three equal 
parts. These are again united at two places by joints, like 
