CARE OF LEVELS
An engineers level is a precision instrument
containing many delicate and fragile parts. It must
therefore be handled gently and with the greatest care
at all times; it must never be subjected to shock or jar.
Movable parts (if not locked or clamped in place)
should work easily and smoothly. If a movable part
resists normal pressure, there is something wrong. If
you force the part to move, you will probably damage
the instrument. You will also cause wear or damage if
you excessively tighten clamps and screws.
The only proper place to stow the instrument
when it is detached from the tripod is in its own
carrying box or case. The carrying case is designed to
reduce the effect of jarring to a minimum. It is
strongly made and well padded to protect the
instrument from damage. Before stowing, the azimuth
clamp and leveling screws should be slightly
tightened to prevent movement of parts inside the
box. When it is being transported in a vehicle, the case
containing the instrument should be placed as nearly
as possible midway between the front and rear
wheels. This is the point where jarring of the wheels
has the least effect on the chassis.
You should never lift the instrument out of the
case by grasping the telescope. Wrenching the
telescope in this manner will damage a number of
delicate parts. Instead, lift it out by reaching down
and grasping the footplate or the level bar.
When the instrument is attached to the tripod and
carried from one point to another, the azimuth clamp
and level screws should be set up tight enough to
prevent part motion during the transport but loose
enough to allow a give in case of an accidental bump
against some object.
When you are carrying the
instrument over terrain that is free of possible contacts
(across an open field, for example), you may carry it
over your shoulder like a rifle. When there are obstacles
around, you should carry it as shown in figure 5-7.
Carried in this manner, the instrument is always visible
Figure 5-7.Safest carrying position for instrument when
obstacles may be encountered.
to you, and this makes it possible for you to avoid
striking it against obstacles.
LEARNING OBJECTIVE: Upon completing
this section, you should be able to interpret
the readings from a leveling rod.
A leveling rod, in essence, is a tape supported
vertically that is used to measure vertical distance
(difference in elevation) between a line of sight and a
required point above or below it. Although there are
several types of rods, the most popular and frequently
used is the Philadelphia rod. Figure 5-8 shows the
face and back of this rod.
Figure 5-8.Back and face of Philadelphia leveling rod.