Plumb Bob:
The
plumb bob is required when measuring the distance along slopes in order to
transfer points to the ground. It is also used for testing the verticality for
ranging poles.
The Compass:
A
surveyor uses a compass to determine the direction of a line. The compass
needle points to the MAGNETIC NORTH POLE and by turning the compass in the
direction of the line being surveyed, the direction of the line can be
observed. Although there are many varieties of compasses, they all fall
into two main categories: either a "plain" compass or a "dernier"
compass.
A plain compass has no adjustment and always reads magnetic
north.
A veneer compass has an adjustable scale that allows for the
"setting off" of the magnetic declination and the compass can then
directly read true north.
The Solar Compass:
The
solar compass is a compass with a very special purpose of easily determining
"Latitude" and "True North". The solar compass was
invented in 1835 by William Austin Burt of Michigan after he had discovered the
iron deposits located in the state and concluded that a regular compass would
give such erroneous readings as to be almost useless. By making
observations on the sun or other stars, the latitude of the location can first
be determined and then "True North" can be determined. The
solar compass also has the ability to measure horizontal angles much like a transit.
The solar compass was such an important invention that within
a matter of a few years it was required by law to be used on the surveys of the
public lands.
William Austin Burt also made another significant
invention. In 1829 he patented the first "typographer", or as
we would refer to it today, the typewriter.
Comments
Post a Comment