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This quality David White
®
instrument has been inspected twice for accuracy before
leaving the factory. The instrument has also been given the best protection possible
against damage during transportation. Even with these precautions, the instrument is
subject to rough handling during shipment. To protect yourself against the possibility
of using an instrument which is out of adjustment, we suggest that you have the
instrument checked by a competent person before using it.
Note: Please read the manual thoroughly before starting the following test.
The following test can be performed to check the instrument’s accuracy:
Set up the instrument in an area that is about 220 feet long and as level as possible.
Place two matching level rods (or drive two pieces of strapping into the ground) about
200 feet apart with the faces toward each other. Position and level the instrument so
that the distance from the instrument to each rod is the same
(measure; Fig. 1).
Take a reading on each rod with the instrument (or mark each piece of strapping where
the crosshair is sighted). Note the difference and record them. Next, move the
instrument to another point in line with the two level rods as shown in Fig. 2. Level the
instrument and take readings on the two level rods (or re-mark the two pieces of
strapping with the new crosshair sightings). The differences should be the same ( A - A'
should equal B - B'). The difference between A - A' and B - B' is the instrument error at
200 feet.
Correction of instrument error should be performed by a competent repair technician.
The instrument should be rechecked periodically to assure continued accuracy.
IMPORTANT!
READ THIS BEFORE USING YOUR INSTRUMENT
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