Troughton & Simms Theodolite

The Proprietors of the Locks & Canals in Lowell, Mass., used this theodolite to lay out the canals that provided transportation and power for the textile mills in that city. It was probably made soon after 1826, when John Troughton took William Simms into partnership and began trading as Troughton & Simms. Exceot for its lack of magnifiers, it is identical to the theodolite described in F. W. Simms, A Treatise on the Principal Mathematical Instruments (London, 1836). The horizontal circle and vertical arc are silvered, and read by verniers to 20 seconds.
The scale for "Diff. of Hypo. & Base" on the back of the vertical arc is used to correlate the angle of elevation or depression with horizontal distances when surveying sloping ground. The signature reads "Troughton & Simms LONDON."
Object Name
Troughton and Simms
overall: 13 1/2 in; 34.29 cm
horizontal circle: 7 in; 17.78 cm
needle: 3 in; 7.62 cm
telescope: 13 1/4 in; 33.655 cm
hanging level: 5 1/4 in; 13.335 cm
place made
United Kingdom: England, London
ID Number
accession number
catalog number
See more items in
Medicine and Science: Physical Sciences
Measuring & Mapping
Surveying and Geodesy
Data Source
National Museum of American History, Kenneth E. Behring Center


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