magnifying glasses.
To avoid unknowingly
dropping a magnifying glass in the field, you
should attach it to a loop of string. The
instrumentman puts his head through the loop,
retaining the string around the neck, and carrying
the magnifying glass in a pocket. At the end of
each day’s work, it is a good practice always to
return the magnifying glass to its proper place in
the instrument case.
Adjusting Pins
Surveying instruments are built in such a way
that minor adjustments can be performed in the
field without much loss of time while the work
is in progress. The adjustments are made by
loosening or tightening the capstan screws that are
turned by the use of adjusting pins. These pins
are also included in the instrument box. They
come in various sizes that depend upon the type
of instrument and the hole sizes of its capstan
screws. Use the pin that fits the hole in the capstan
head. If the pin is too small, the head of the screw
will be ruined.
Replacements for these pins are generally given
free of charge by surveying instrument dealers.
Like the magnifying glass, adjusting pins should
be carried in the pocket and not left in the
instrument box while a survey is in progress. This
will save a lot of valuable time when the pins are
needed. Do not use wires, nails, screwdrivers, and
the like, as substitutes for adjusting pins.
Tape Repair Kit
Even though you handle the tape properly and
carefully during field measurements, some tapes
still break under unforeseen circumstances.
During chaining operations, when the area is quite
far from the base of operations, the surveyor
should always be sure to have a tape repair kit
(fig. 11-55) with him so that he can rejoin any
broken tape in the field, or if the surveyor has
brought an extra tape, he can take the broken tape
back to the office to be repaired.
The tape repair kit usually contains a pair of
small snips, the tape sections of proper size and
graduations, a hand punch or bench punch with
block, an assortment of small rivets, a pair of
tweezers, a small hammer, and a small file. Before
reusing a repaired tape, always compare it with
an Invar or Lovar tape to check it for accuracy.
FIELD SUPPLIES
Field supplies consist principally of a variety
of materials used to mark the locations of
points in the field. For example, pencils, field
notebooks, and spare handles for sledgehammers
45.781
Figure 11-55.-Tape repair kit.
11-46
