Camera With 2 String Galvanometer

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Item Camera With 2 String Galvanometer
Item code
Manufacturer O.S. Petty
Circa 1926
Donor Petty Geophysical
Location Bob Bullock Texas State History Museum
Serial number
Taxonomy GSH281A

Used in prototype recorder in 1925. Synchronous motor driven by 50 cycle per second tuning fork (10) turns spoked wheel five revolutions per second. One of the 10 spokes on wheel cuts off light passing through galvanometer each 1/50 second. The wider spokes mark l/l0th and 1/5th seconds.