C 54 ] 
The Divifions arc determined by means of a Cat-gut 
Line ftretched perpendicularly with the Box as near 
the brafs Edge as may be, that the Parallax arifing 
from a different Pofition of the Obferver may be as 
little as pofllble. 
Underneath the Card arc two fmall Weights, 
Aiding on two Wires, placed at right Angles to each 
other 5 which, being moved nearer to, or farther 
from the Center, counterbalance the Dipping of 
the Card in different Latitudes, or reftores the Equi- 
librium of ir, where it happens by any other means 
to be got too much out of Level. 
There is alfo added an Index at the Top of the 
inner Box, which may be put on and taken off at 
plcafure, and ferves for all Altitudes of the Object. 
It confifls of a Bar, equal in Length to the Diameter 
of the inner Box; each End being furnifhed with a 
perpendicular Stile, with a Slit parallel to the Sides 
thereof. One of the Slits is narrow, to which the 
Eye is applied, and the other is wider, with a fmall 
Catgut ftrctch'd up the Middle of it, and from thence 
continued horizontally from the Top of one Stile 
to the Top of the other : There is alfo a Line 
drawn along the upper Surface of the Bar. Thefc 
four, viz. the narrow Slit, the horizontal Catgut 
Thread, the perpendicular one, and the Line on 
the Bar, are in the fame Plane, which difpofes itfclf 
perpendicular to the Horizon, when the inner Box 
is at reft, and hangs free. This Index does not 
move round, but is always placed on fo as to an- 
fwer the fame Side of the Box. 
When the Sun’s Azimuth is defired, and his 
Rays are ftrong enough to caft a Shadow, turn 
about the wooden Box, till the Shadow of the 
horizontal 
