Timber Estimator

Measuring the Land and its Wealth

c. 1850 – c. 1950

Richard Paselk, Curator

Clinometer/Timber Estimator

Timber Estimator

Maker unknown

sn: 32

c. 1910; private collection

By sighting the top of a tree from a given distance the instrument gives an estimate of the number of logs that could be cut from the tree. A summary of the instrument use provided in the patent by the inventor is reproduced below in the text box. A complete copy of the patent is also provided here in pdf format for the reader's convenience.

text box from patent describing the use of the timber estimator

Description

The sighting tube is made of 1/2” square chemically darkened brass tubing, with a pinhole-eyesight and a wire through the pin holding the scale-piece. The weighted, semicircular scale is of chemically blackened cast bronze with an integral plumb weight. A view of the instrument from the eyepiece end and held as if in use, is seen below. The original, non-linear, scale is numbered with aligned cuts through the arc from 0–16, as shown in the close-up photograph, such that when sighting the wire in the sighting tube it would line-up with the cuts and the numbers are visible. It is stamped on the sighting tube face of the plumb weight: PAT. MAR. 8 1904 No 753940, and on the front face: 32 (serial number?). The instrument and its original leather carrying case are in very fine to excellent condition.

Eyepoint view of instrument as if in use

Close-up photograph of non-linear, scale

When acquired the current specimen had been modified, apparently to read the tangent of an angle directly. A second scale, of thin, polished copper, had been soldered (lo temp Sn/Pb solder) on over the original scale (the original scale was partially visible on the exposed edge). The added scale has a double, symmetrical scale stamped from 19–1–1–19 stamped into it with divisions incised into the copper. A series of v-notches were filed into a solder bevel such that when sighting the wire in the sighting tube it would line-up with the notches.The copper scale and solder were removed to restore the instrument to its original condition December 2011 (Richard Paselk), again giving direct readout in logs.