Surveying - Carpenter's and Builder's Math, Plans, and Specifications - page 214

R

U

U

T
P

V

Q

S

V'

X

Y

O

Z

O

J

N

H

D

L

K

M

V

B

F

A

E

C

G

Figure 6-8 The transit. In the illustration, A represents the
lower plate; B, the upper plate; C, the central dome; D, the
divided limb; E, the spindle; F, the foot screws; G, foot-screw
cups; H, the vernier plate; J, the compass circle; K, the clamp-
screw vernier plate to divided limb; L, the tangent screw; M
and N, spirit levels; O, standards or supports; P, the horizon-
tal shaft; Q, the vertical arc; R, the objective; S, the ocu-
lar; T, the telescope; U, racks and pinions; V, the adjustable
cross-hair ring; v, the divided-limb vernier; v , the vertical-arc
vernier; X, the spirit level; Y, the gradienter; and Z, the scaled
index.

in leveling the instrument. The screws pass through the ends of the
arms of the upper plate. They are surmounted by dust caps. There
the feet fit into small cups, G , that rest on the top surface of the
lower plate to avoid wear.

Shifting Center
Since these cups, as well as the central part of the lower plate, may
be moved (after slightly loosening the foot screws), a slight motion