Pitot-Darcy Tube

The Pitot tube, a simple device for determining the subsurface flow of water, is a hollow tube with a bend at the bottom that can be turned to face the flow. A French engineer named Henri Pitot described the form in 1732. Henry Darcy, the Inspector General of Ponts et Chausées in Paris, discussed various improvements in the 1850s.
This example is 96 inches long. It came from the Proprietors of the Locks and Canals in Lowell, Mass., and was probably used by the resident engineer, James B. Francis. Francis did not mention an instrument of this sort in the 1855 edition of his Lowell Hydraulic Experiments, but in the 1868 edition he talked about tubes of about two inches diameter and various lengths.
Ref: James B. Francis, Lowell Hydraulic Experiments (New York, 1868), p. 172.
Object Name
date made
after 1850
overall: 96 in; 243.84 cm
ID Number
accession number
catalog number
See more items in
Medicine and Science: Physical Sciences
Measuring & Mapping
Water Currents
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Proprietors of the Locks and Canals

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