H.S. Pearson gauging rod: A tool analysis

Chronicle of the Early American Industries Association, Inc., The, Sep 2000 by Packham, Jim

Gauging rods and wantage rods were used to measure the capacity and contents of casks, by merchants in the buying and selling of liquids, and also by government officials in determining the amount of excise taxes to be paid, especially on alcoholic beverages. Thus the gauging rod has been an economically important measuring tool since at least early in the 17th century.

The Directory of American Tool Makers (DAT)' lists Henry Sleeper Pearson ( 1789-1878) of Portland, Maine, as "a watchmaker who also made mathematical instruments, including survey compasses." The DAT entry shows only secondary sources for this tool maker. A gauging rod marked "H. S. Pearson. Maker. Portland" (Figure 1) exists to confirm the DAT listing with a tool source. This Pearson gauging rod was acquired at the Brown Auction in the fall of 1999 for less than the usual cost of similar antique tools because it obviously has had a repair and lots of use, but it still offers an opportunity for information and analysis.

The rod itself is maple, 48 inches long with a rectangular cross-section approximately 5/a x g/4 inches. The zero end of the rod is tapered and brass-tipped. Side one has a scale from 0 to 48 (inches) with hand-stamped, ink-filled numbers at one inch intervals with subdivisions of tenths of an inch. The decimal subdivisions would be helpful if a user were making long-hand calculations of the capacity of a cask from its key measurements of head diameter, belly diameter, and length.

Side two is scaled from o to 200, numbered at intervals of ten units and with subdivisions in tenths. It has been checked by calculation that these numbers would indicate capacity in U.S. gallons when the gauging rod is used to measure the "diagonals" of a set of similar casks. Figure 2 lists a few points of correspondence between diagonal lengths and gallonage as marked on the Pearson rod. The volumes of various sizes of casks will be proportional to the cube of the length of their diagonals if all of the casks are of similar shape. This relationship and other principles of barrel gauging are outlined in an earlier issue of The Chronicle.

Sides three and four of the rod have tables that contain "wantage" data for six sizes of casks. (Side three also has the maker's imprint.) Parts of these tables are too faint to get reproducible images, but Figure 3 replicates all six tables. There are several observations that can be made from study of these wantage tables.

The Pearson rod requires the user to determine the gallonage wanting from the appropriate table after measuring in inches from the inside of the bung hole to the liquid surface. The tables apply only to casks lying on their sides. Most gauging and wantage rods provide wantage measurements with direct reading scales calibrated in gallons. Some wantage rods have scales for standing casks as well as lying casks. Interestingly, the Pearson wantage tables list depth to the liquid in inches and quarters of inches even though the rod is scaled in inches and tenths of inches.

The six cask sizes and the names applied to them do not match the formal U.S. liquid capacity system, within which a "barrel" is 31.5 galIons, a "tierce" is 42 gallons, a "hogshead" is 63 gallons and a "pipe" is 126 gallons. Nor do the Pearson sizes and names quite match those on other typical U.S. wantage rods. For example, a Belcher Brothers & Co.s ( 18531885) wantage rod names its 84 gallon line a "puncheon" and there is a line for a 120 gallon "pipe" as well as a 120 gallon "hogshead." This is a reminder that cask capacities and names varied noticeably over time and in different locations.

Because cask names did not always represent the same capacities, it became common practice for wantage rods to identify the "Belly Diameter" (B.D.) of the cask to which the wantage scale applied. Figure 4 lists some of the B.D.'s shown on a Belcher wantage rod compared with the diameters implied by the wantage tables of the Pearson rod. The diameters are almost identical; coopers made tight casks with remarkably similar proportions, for similar capacities, regardless of the names of the casks.

It is not possible to date this tool, but out of Pearson's 89 year life, he could have been making signed instruments from about 1810 to about 1870. This gauging rod might be from the first half of that time, prior to the efforts of the 1830s to standardize weights and measures throughout the United States.

At some time long ago, this Pearson rod had been broken at about the 12.2 inch (5 gallon) mark. Fortunately for this study, the maker's imprint was not damaged. A new piece of maple was fitted into a jagged break and re-marked with the appropriate inch and gallonage lines and numbers. The repair was exceptionally well done and is only noticeable because of the lighter tone of wood. Under a magnifying glass, it can be seen that the numbers in the repaired area were made with a slightly different set of stamps than Pearson had used originally. This difference raises the possibility that the repair was done by someone else, or perhaps by Pearson after he had acquired new stamps.