140 Mr. Wollaston's Description 
smallest wire capable of supporting a plummet eclipses them 
entirely. 
There is of course a level (and a very sensible one it is) 
for adjusting the axis. The circle was ordered to have ten 
radii 4 that when the telescope is horizontal, and pointing to 
a meridian mark, there might be a vacancy between the cones, 
above or below, for introducing a level. In the brace be- 
tween the pillars, over the moveable Y, (at A, Tab. XV. ) it may 
be observed, the bottom bar is omitted ; in order to give the 
better room for passing the level, without inclining it, or run- 
ning any hazard of striking it. From the lower bar of the 
opposite brace B, over the fixed Y, there stands out a forked 
piece of brass, to receive the leg of the level, and direct it to 
its place ; as also for keeping it upright when the foot stands 
on the pivot, and just allowing a very little shake, so as not 
to cramp it. By this contrivance the level is easily handled, 
and reversed, without danger of disturbing it or the instru- 
ment. 
The top plate, as may be seen in the drawing, has a large 
opening cut more than half way across it. The design of this 
is, to allow you to observe quite up to the zenith, and a little 
beyond it, clear of all obstruction whatsoever. And since 
the whole instrument is capable of being reversed, or turned 
half way round in azimuth ; when you have occasion to ob- 
serve the transit of stars, in that part of the heavens where 
they would be intercepted by the plate in one position, it 
is entirely out of the way in the other. 
The circle itself is of full two feet diameter at the divi- 
sions ; being 254 inches at the edge. The undivided circle, 
on the side of the telescope next to the open end of the axis, 
