Page 31 - My FlipBook

INSTRUMENTS AND INSTRUMENTATION. 27

2. Measure the length of the
blade in the gradations on the prin-
cipal shaft, which gives the length
of the blade in millimeters. This
is the second figure of the for-
mula.
3. Measure the angle of the
blade with its shaft by laying the
handle of the instrument on the main
shaft of the gauge, parallel with the
lines, and bringing the blade (turned
toward the small numbers) parallel
with one of the gradations of the cir-
cular head. This will give the angle
of the blade with the shaft in centi-
grades or hundredths of the circle.
This gives the third figure of the
formula.
These formulee are stamped on
the handles of the excavators.
Plugger points may be meas-
ured and designated in a similar
manner.
The diameter of burs may be
obtained by measurement in the
slot.

The Ordinaries.
The set of ordinaries is made
up of hoes and hatchets ; nine
hatchets and nine hoes, or eighteen
instruments. In these there are
three widths and lengths of blade
(three sizes) and three angles of
blade, no more and no less The measurements of these make
up the formula.