Surveying - Carpenter's and Builder's Math, Plans, and Specifications - page 217

Controlling Clamps
A screw K permits clamping of the vernier plate H to the divided
limb D . Another screw attached to the upper plate permits clamping
of the divided limb to the upper plate.

Tangent Screws
One tangent (or slow motion) screw L accompanies each clamp
screw. It is used to complete the clamping at the exact spot where
the clamp is to be made.

Spirit Levels
The spirit levels are attached to the vernier plate—one level M in
front (north point of the box), the other N on the side—thus forming
an angle of 90 ◦ .
Standards
The vernier plate carries two vertical standards or supports O ,
which are shaped like an inverted V and placed one on each side.
The center of their legs is just opposite the 90 ◦ graduation of the

compass box. They are made equal.

Horizontal Axis
The standards carry between and on the top of them a movable
horizontal axis P .

Vertical Code
To the horizontal axis is attached, by means of a clamp screw, a
vertical circle or arc, Q , that is divided like the horizontal circle in
its vertical motion just touches a circular vernier v

carried by the

left standard together with a slow-motion screw.
Telescope
In the middle of the horizontal axis and perpendicular to it is at-
tached a telescope T of a description similar to that of the engineer's
level, with an objective R and an ocular S , racks and pinions U for
their motions, and an adjustable crosshairs ring V, with ordinary
and stadia hairs.

Telescope Level
An adjustable spirit level X is also attached to the under part of the
telescope, as in the engineer's level. This permits the transit to also
be used as a leveling instrument, if necessary.

Motions of the Telescope
The telescope can function over the full range of the horizon and can
measure any horizontal angle. In addition, since the telescope is on a