High Speed Indicator, a Revolution Counter

High Speed Indicator, a Revolution Counter

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To count revolutions of the shafts that ran machinery, engineers used counters like this one. The manufacturer, L. S. Starrett Company of Athol , Mass., called the device a speed indicator, although it has no timekeeping apparatus. The steel counter has a flat handle on one side and a rotating cylindrical rod on the other. In between is a flat curved case on which a dial is mounted. Pressing the rod against a rotating shaft rotates it and advances the dial. The edge of the dial is divided into 100 equal parts, which are numbered from 10 to 100 by tens. Two different nozzles fit into the far end of the cylinder. The instrument fits in a red, white, and black paper box.
A mark on the dial reads: THE L. S. STARRETT CO. (/) ATHOL, MASS. U.S.A. Another mark there reads: PAT. APR.13.97 (/) MAR.28.05
This counter is one of the many inventions of Laroy Starrett (1836-1922), who was born and raised on a farm in Maine. In 1880, having successfully patented and sold a meat chopper, as well as shoe studs and hooks, Starrett established a business in Athol, Mass., to sell drawing instruments and small tools. He applied for a patent for a speed indicator in 1895, and received it in 1897.
Stafford P. Walsh of San Francisco, Ca., improved on the instrument, assigning his patent to L. S. Starrett Company when it was granted March 28, 1905. The device sold in at least three models. This is No. 104, which was particularly intended for high speeds. It was sold both directly by Starrett and through distributors of tools and steam engine equipment. This speed indicator is mentioned in Starrett catalogues into the 1930s.
L. S. Starrett, “Speed-Indicator,” U.S. Patent 580,432, April 13, 1897.
S. P. Walsh, “Speed-Indicator,” U.S. Patent 786,073, March 28, 1905.
“Laroy S. Starrett,” National Cyclopaedia of American Biography, 18, New York: J. T. White and Company, p. 428.
L. S. Starrett Company, Catalogue, Athol, Mass., about 1937, p. 192.
Currently not on view
Object Name
counter, analog
date made
ca 1910
L. S. Starrett Company
place made
United States: Massachusetts, Athol
Physical Description
steel (overall material)
paper (overall material)
overall: 2 cm x 14.3 cm x 5.4 cm; 25/32 in x 5 5/8 in x 2 1/8 in
ID Number
catalog number
accession number
Credit Line
Edith R. Meggers
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Data Source
National Museum of American History
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"Some more information on this item for you.Starrett had 4 speed indicators that they sold.A) The #102 was sold from the mid-1880's to the early 1890's. This speed indicator was the Woodsman type speed indicator and referenced Woodsman's patent. It is most likely that Starrett purchased the patent from Woodsman and took over manufacture of the indicator.B) The #104 was sold from the early 1890's until 2000.C) The #106 (Improved Speed Indicator) was sold from the early 1890's until 1971.D) The #107 (Registering Speed Indicator) was sold from 1897 until 2000.These speed indicators were made to be used in conjunction with a stopwatch. The machinist would set the counter to zero, put the indicator on the shaft to measure the speed and then pull the indicator off the shaft after a certain period of time (often somewhere between 10 and 30 seconds depending on shaft speed). Calculating the shaft RPM was a simple calculation."

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