WOODEN SURVEYING COMPASSES
by David G. Krehbiel
Early American craftsmen were faced with the need for tools and instruments to further the country's development, but they were handicapped by the lack of financial resources to import the required materials and metals. So they turned to the most available and plentiful source of material - wood.
Wooden materials were produced during the approximate period from 1750 through 1825. Using wood to make land surveying compasses was a natural application for the craftsmen as they were making ship's compasses from wood. Marine compasses were commonly made from closely grained tropical woods that contained oil and thus resisted salt water and sea air.
The types and combinations of wood used to make surveying compasses varied. Some were of a single type of wood and still others were of combinations of wood and brass.
The most prominent type of surveying compass was the plain compass. It was made of walnut, applewood or mahogany with wooden sights that fit into square holes at each end of the main plate. Compass cards were usually made of paper, and the jacob's staff or tripod holder consisted of a separate piece of wood approximately one inch thick attached to the bottom of the main plate of the compass.
Variations on the plain compass include wooden sights that extend below the wooden plate and are held in position by wooden plugs; brass fixed or folding sights; engraved compass cards; brass needle circles; and brass sockets for the staffs or tripods. A few rare compasses featured wooden level vial cases.
When making wooden surveying compasses, craftsmen duplicated the brass constructed compasses in a piece of wood that was thicker than the brass plate. The circular body of the main plate would be hollowed, and a compass card, pivot and needle would be installed. The compass would then be covered with a piece of glass and sealed with putty.
It is surprising to note how many of these instruments have survived the past 150 to over 200 years. Smart's book The Makers of Surveying Instruments in America since 1700, lists nearly 20 makers of wooden surveying compasses. Bedini's book Early American Scientific Instruments and Their Makers, lists 31 wooden compasses in public and private collections. Of these, 13 different makers are identified; eight instruments remain unidentified.
Each year, two to three wooden compasses become available to the collector through national scientific instrument dealers. Prices in 1989 on these instruments range from $1000 through $2000. In my years of collecting, I have yet to become aware of a wooden instrument that is available from a private source or party.
-First published in the Bell Laser & Surveying Equipment Company newsletter "P.O.L.", Vol. 1, No. 6, July/August 1989.