SIY12.TXT      The Next Step Up                                             58

                                  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 $270.

A Suunto KB-20 compass in a steady hand or on a monopod will yield about the
same results for $25.  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 $400.  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 $800. 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.  There is surely no land around here worth that much trouble.

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 between $100
and $200.

If you need to read many inclinations, an Abney level is much handier that the
clinometer on the Ranger.  An Abney level costs between $75 and $150.

Dave Beiter, CAVE Inc, 1/2 Fast Road, Ritner, KY 42639 606/376-3137

 SIY12.TXT      The Next Step Up                                            58«

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?