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Differential Resonator

Unidentified · Psychology

This metal tube is mostly closed at one end, except for a small pinhole. The other end is closed as well, but from the metal cap protrudes a smaller pipe with a closely ridged piece set on it. A metal knob in this same cap controls the extension or retraction of this smaller tube, which is etched with an unmarked measurement scale.

Accession Number: 2013.psy.150

Alternative Name:

Primary Materials: Metal


On the body of the tube: “Manufactured by Consolidated Optical Co. Ltd Toronto”.

Dimensions (cm): Height = 15.5, Diameter = 4.2


This is an acoustical instrument designed to resonate at an adjustable audio frequency and thus act as a detector for a range of frequencies. The piston allows the resonant chamber to be expanded or shrunk to match different frequencies. It was likely used in experiments relating to hearing.


Very Good. Some minor tarnishing and scratches.

Associated Instruments:


The Consolidated Optical Co. Ltd Toronto

Date of Manufacture: 1912-1925


University of Toronto Department of Psychology

Additional Information and References:

This instrument was designed by Edward H. Murfee of Gainesville, Georgia, who received a patent for it on November 12, 1912. Murfee’s patent (US1044227A) describes the instrument like this:

“This invention relates to resonators and has for an object to provide a device of this character that may be adjusted to resonance.

Most resonators of ordinary construction respond to but a single tone and therefore the principal object of the present invention is to provide a resonator which may be easily and quickly adjusted to respond to any tone for which it is adjusted. This adjustment of the device to resonance is effected through the instrumentality of a movable piston within a tube which is open at one end, the piston forming an adjustable bottom for the tube, and furthermore having a hollow stem or piston rod which forms means for manipulating the piston and for leading the sound therefrom to the ear.”

An identical instrument, also by The Consolidated Optical Co. survives in the US National Museum of American History (Smithsonian) collection: Different Resonator. (ID Number: PH.315741 catalog number: 315741 accession number: 217544)

Historical Notes:

  • Donated to UTSIC