 SIY12.TXT      The Next Step Up                               67


                           Chapter 12


                        The Next Step Up


The error involved in this surveying method is approximately 1%,
or a precision of 99%.  This is due to reading the compass to
only one degree.

If 99% precision is not acceptable, a better compass can be
used.  A Brunton pocket transit type compass on a tripod can be
read to a quarter degree.  This results in an expected error of
0.45%.  The cost of the Brunton Pocket Transit and tripod is
approximately $350.

A Suunto KB-14 compass in a steady hand or on a monopod will
yield about the same results for $100.  Unfortunately, the Suunto
only functions on level ground.  Also, you cannot use it for a
protractor and ruler to plot your map.  There is also a "rivalry
error", introduced by the interaction of the virtual sighting
mechanism and some quirks of human stereoscopic vision.

A staff compass or forester's compass can be read to about a
quarter degree also.  The "staff" refers to a Jacob's staff, a
one footed tripod.  The cost is about $500.  There are several
models.

The next improvement in the instrumentation is a telescopic
compass.  These are accurate to about a tenth degree.  The
expected error is approximately 0.15%.  A telescopic compass and
tripod costs approximately $1000.  Several models.

The magnetic field of The Earth is not accurate to a tenth
degree.  You will have to be aware of magnetic storms if you try
for this sort of precision with a compass.  It is not only
getting expensive, but it is getting to be a lot of trouble too.
This book is supposed to be a poor man's guide to surveying
quickly, easily, and inexpensively.

To obtain errors of less than 0.1%, or a precision of 99.9%,
requires the use of even more expensive and delicate
instrumentation; a transit or theodolite.  I never have had any
use for this sort of precision.  This is the realm of the civil
engineer.  I have never found any land around here worth that
much trouble.

 SIY12.TXT      The Next Step Up                              68


If you have a lot of preliminary surveying to do, an improved
method of measuring distance is available.  A small device called
a stringbox will quickly measure distance without an assistant.
A thread is pulled over a rotating counter, and the distance is
read on a dial.  These cost about $125.

If you need to read many inclinations, an Abney level is much
handier that the clinometer on the Ranger.  An Abney level costs
about $100.

This software package seems to be evolving into three different
products; the present preliminary surveying, simple plotting of
deed descriptions, and 3-D scientific surveying.

I need good examples.  Wanna be an example?

Copyright (c)1995 by David Perry Beiter

If you have any questions, problems, or comments, write or call
me.
Dave Beiter, CAVE Inc, 1/2 Fast Road, Ritner KY 42639.
606/376-3137.
MCI Mail: 635-1762
byter@mcimail.com
X.400: c=US;a=MCI;s=BEITER;d=id=6351762
CIS: >MCIMAIL 635-1762 (be sure to include your name in the text)

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