William Fox’s short “History of the Lumber Industry of New York State” in the Sixth Annual Report of the Forest, Fish and Game Commission (1901) includes a photograph (shown here) of a crew scaling and marking logs at a skid way.

Scaling is the term used for the measurement of logs to determine their usable wood content.  When developing tables for log measurements, certain assumptions were made concerning natural variations in diameters (log’s thickness inside the bark) and reductions for waste due to unseen defects, saw kerf (saw width) and slab loss at the mill. 

During the 19th Century and afterwards, mills in most lumbering regions of the United States measured and sold lumber by a price per thousand feet unit measure.  Feet in this case is the amount of square edged board contained in the log, one “foot” being a board 1 inch thick by 12 inches long by 12 inches wide (144 cubic inches).  When sold by this unit measure, the log’s diameter and length was compared to mathematical tables containing the board feet.  In addition to variable diameters, this method was appropriate where multiple lengths of logs were cut.  One commonly used rule for this type of measurement was the Doyle Rule.

However, in regions such as the Adirondacks, logs were sold piecemeal and were scaled in proportion to an established standard length and diameter.  This standard size log was called a market and was this region’s unit of measure.  Logs were cut the same length while their diameter was scaled, rounded to the inch or half inch, in proportion to the market’s diameter.

The Adirondack Standard (Market) Rule

The Adirondack standard’s value for a market log was a log 19 (22 inches in the Saranac River region) inches diameter and 13 feet in length. Logs were typically cut up to four inches longer to allow loss to towing and river drives, but buyers and sellers were aware of this variance.  Board footage resulting from 5 markets equaled 1,000 board feet, so parties to a transaction in the Adirondack region would know how many markets of logs were necessary to amount to the board footage desired.  Log lots were exchanged based on the number of markets, the number of whole markets and “market equivalents.”

What are “market equivalents”?   Since not all trees cut to a 13 foot length in a typical wood lot by nature would be 19 inches thick, market decimal values, or equivalents, were calculated using a formula.

The market equivalent value of a thirteen foot log was determined by dividing the square of the log’s diameter by 361, the square of a market log value of 19.  The answer was the log’s market equivalent value.  For example, the market value for a log with a (smaller than market) diameter of 17 inches would be 0.801, (17 x 17)/ (361); a (larger than market) diameter of 24 inches would be 1.596, (24 x 24)/ (361).  Consequently, only a log with a diameter of 19 inches would have a value of 1.

The crew in the photo was tasked with determining the total markets represented in the stack of logs.  One uses a ruler to measure the diameter of each log in inches.  They would have used rulers or calipers inscribed for diameter measurement by inch, though also inscribed with Doyle Rule measurements for board footage.

Typically, the result is recorded on a Tally Board (or “paddle”) on which a two column form might be attached.  One column contained a list of possible diameters and the other used for entering the count of logs matching that diameter.  A third column was sometimes used to count diameters by tree species.  Typically, quantities in the field were noted by symbols of dots or slashes.

To determine the total value of markets in the log stack, the scaler would return to the field office with the tally board and transfer and tabulate the counts to a form using the decimal market equivalent explained above.  In this way, the crew in the field is not determining board footage; they are determining the total number logs of each diameter in that stack of logs.

Gradually, the Adirondack Standard would be replaced by the Doyle Rule in the Adirondacks.

The Doyle Rule and the Doyle Ruler

Some loggers in the Adirondacks, particularly the western section, cut their logs in 12, 14, 16 or other size lengths, sold their lumber by the 1,000 board foot measure and typically used the Doyle Rule.  This rule was named for Edward Doyle who developed it around 1825.  Later (1846), J. M. Scribner developed another rule table and, after publishing it for years, replaced it with Doyle’s rule in his books.  Both rules used a formula to calculate board footage based on the height (or length), diameter, and different wood loss assumptions.

Log scaling teams would record the diameter and length and read the board feet value from rulers, as described above, which functioned as Doyle Rule tables usable in the field.  Some rulers were inscribed “Doyle Scribner”.  By 1910 the Doyle Rule would be combined with the Scribner Rule to adjust for fallacies in their calculations for large and small logs.  The scaling ruler would use Doyle measures (Scribner’s considered too high) for smaller logs and Scribner measures (Doyle’s considered too high) for larger logs.  Typically, the 36-inch diameter was the point at which Scribner’s values were used.  (Lumbermen believed that the Doyle Rule loss allowances for saw kerf (25%) and slabs (4“) were too great).

Note the numbers 8, 10 and 18 at the top of the ruler.  These numbers are for three different lengths of a cut log or standing tree.  Along the ruler in line with these three numbers are other numbers: 8 (2-5-8-etc.), 10 (3-6-10–etc.) and 18 (5-10-18-etc.).  These three series of numbers are an inch apart and represent the calculated board feet, rounded to the foot, for each subsequent inch of diameter of the log or tree.

The Doyle Rule math formula for calculating board footage, where the diameter is D and log length is L, is as follows:  Subtract 4 from the determined diameter in inches, square ¼ of the answer and multiply this answer by the length (((D-4)/4)²) x L).  For a log 18 inches long and 8 inches diameter, the board footage is, by steps:  8-4=4; 7/4=1; 1 squared is 1; 1 x 18 = 18.  The answer from the ruler is 18.  A little tedious, but the Doyle Scale Ruler provides a quick answer in the field for the log’s board footage.  If a diameter is larger than the ruler, two measurements were made and the two results for the log’s board footage added together.

The Doyle, the Scribner Decimal (Scribner decimal footage tenth numbers in its table were rounded to the foot, i.e., 6.4 = 6) and the International ¼ (assumed loss of ¼ inch saw kerf) Rules are the three major scaling rules in use today.

Additional Scaling Tools

Though not used for scaling the logs,  early in the 18th century, a means was needed to mark the logs being driven down a river used by various loggers. This symbol or log mark identified that log as belonging to that company and were sorted downriver with others for that company.

In the photograph above, a team is hammering the company’s symbol several times on the log so that at least one mark can be read after its rough ride down the river, surviving bouts with rocks and other logs, or even dynamite if it was part of a jam.

Another tool for scaling lumber was a caliper rule for scaling standing timber.  Scalers must also estimate board footage on lots where the trees have not been cut.  This caliper is ruled by inch and used for measuring the diameter of the tree at about eye level.  The height of the tree was determined by a logger’s experienced, visual estimate, use of shadows of the tree in sunlight, use of surveying tools and other methods that use triangulation.

Also used was a caliper log scaler with a five-foot wheel.  These were developed and made by manufacturers such as F. M. Greenleaf of Belmont, MA (and Littleton, NH) and C.W. Grover of Caratunk, ME shortly after the turn of the 20th Century.  The spiked wheel was for measuring the length of the log within six inches.  The measurement is started with point of the black, lead weighted spike (so gravity would force it to be the starting point) and the wheel is moved along the length of the log.  Each spike point is six inches apart and stripes, for this wheel, on every second spike represent one, two, three and four foot measured with the touch of the lead spike being a five foot measurement, hence the wheel’s name.

Today, similar scaling rules are used with various assumptions for wood loss. Also, in recent years, loggers are turning in some instances to laser technology to determine board feet from lumber.  But a hundred years ago, mill contracts in the Adirondacks included the term “market” for the lumber to be milled and sold. A buyer needed to know how many markets would result in the total of board feet he required for a building project.

Photographs: men scaling and marking logs and list of log marks (1901 Forest Fish and Game Commission Report); Tally Board, Doyle Scale, Doyle Ruler (photos taken at the Adirondack Museum’s Logging Exhibit); and Caliper Wheel (Photo by Richard Walker, Courtesy Adirondack Museum).