electromagnetic tuning fork Lissajous comparator
Date: circa 1870
Inventory Number: 1997-1-0929
Classification: Tuning Fork
Subject:
Maker: Louis Jules Duboscq (French, 1817 - 1886)
Cultural Region:
Place of Origin:
Dimensions:
50 x 44 x 22 cm (19 11/16 x 17 5/16 x 8 11/16 in.)
Description:
The wooden stand supports an electromagnetic tuning fork set horizontally. The base of the stand has a leveling screw. A sliding double-weight is attached on each tine of the fork. A scale in centimeters from 0 to 24 is also engraved on both tines. At the end of one tine is a silvered mirror and at the end of the other is a star wheel, which acts as a counterweight. Two electric connectors are also visible: one to power the electromagnet, one to be used as an interrupter. The fork can be rotated so the mirror vibrates in the horizontal or vertical planes.
As several other acoustical instruments in the collection, this one has an old location number inscribed on an oval paper glued to the base: 19-3-2. There is another old location number stamped on this instrument: 23-21.
As several other acoustical instruments in the collection, this one has an old location number inscribed on an oval paper glued to the base: 19-3-2. There is another old location number stamped on this instrument: 23-21.
In Collection(s)
Signedon both tines: DUBOSCQ / A PARIS
FunctionTogether with another similar comparator (1997-1-0930), this instrument is used for compounding and comparing vibratory movements by the Lissajous optical method.
Lissajous figures or curves are constructed from complex harmonic motions. They are often used to measure a phase difference between two vibrations.
An example of how such figures are generated is found on the following website.
Lissajous figures or curves are constructed from complex harmonic motions. They are often used to measure a phase difference between two vibrations.
An example of how such figures are generated is found on the following website.