Scale RulesRules for Drafting
To create technical drawings such as those presented by the traveling exhibition, Doodles, Drafts, and Designs, draftsmen needed drawing instruments with specialized scales. Most often, their goal was to represent a real-life place or object at a reduced proportion. Thus, drafting rules like those shown on this page were typically marked for making drawings at scales such as 1/8-inch to 1 foot. Sometimes, instead of marking the increments throughout a scale, only the first and last segments of a scale were subdivided to the desired proportion. These were called open divided or architect's scales.
Rules for drafting sometimes had plotting scales. These were divided into equal increments of a useful length, such as 1/2-inch, that could be directly transferred to a drawing such as a surveying map. At both ends, plotting scales typically had diagonal scales. These allowed users to reasonably accurately estimate the decimal division between two markings on a scale. Instruments in this category also may have a line of chords. This projected the distance between the end of a quarter-circle arc and each of the degrees along the arc onto a straight line. Finally, the scales for measuring lengths on rules for drafting were often divided into multiples of 1/10-inch, called chain scales, which were advantageous for activities such as construction or machine work.
"Scale Rules - Rules for Drafting" showing 1 items.
- Four scales of inches are on this two-sided, 12-inch steel rule used for engineering drawing. On one side, nine inches of one scale are divided to 1/10", one inch is divided to 1/20", one inch is divided to 1/50", and one inch is divided to 1/100". Ten inches of the other scale are divided to 1/16", one inch is divided to 1/32", and one inch is divided to 1/64". The ruler is marked: D. & B. (/) BANGOR Me. (/) U.S. Stnd. It is also engraved: W.A.L.
- On the other side, ten inches of one scale are divided to 1/12", one inch is divided to 1/24", and one inch is divided to 1/48". Eleven inches of the other scale are divided to 1/14", and one inch is divided to 1/28". The ruler is engraved: W.A.L.
- A farmer and sawmill owner turned toolmaker, Samuel Darling (1815–1896) apparently first made machine tools in 1846. He built a dividing engine and partnered with Edward H. Bailey in Bangor, Me., in 1852. The next year, Darling received his first patent and bought out Bailey, and by 1854 he was in partnership with Michael Schwartz of Bangor. That business lasted until Darling moved his craftsmen and equipment to Brown & Sharpe's Providence, R.I., workshop in 1866. Thus, this object was made between 1852 and 1853. For a drafting tool invented by Darling, see 1977.0460.01 and 1990.0317.02.
- An unidentified relative of Erasmus Darwin Leavitt Jr. (1836–1916), the renowned American mechanical engineer and designer of steam engines, owned this rule. (None of Leavitt's children had names that began with "W," and his father's name was also Erasmus.)
- References: Samuel Darling, "Apparatus for Grinding and Shaping Metals" (U.S. Patent 9,976 issued August 30, 1853); Davistown Museum, "Registry of Maine Toolmaker Listings," http://www.davistownmuseum.org/TDMtoolMakers.html; Henry Dexter Sharpe, A Measure of Perfection: The History of Brown & Sharpe (North Kingston, R.I.: Brown & Sharpe, 1949), http://www.roseantiquetools.com/id44.html.
- Currently not on view
- date made
- Darling, Samuel
- ID Number
- accession number
- catalog number
- Data Source
- National Museum of American History, Kenneth E. Behring Center