This is a four-sided box-shaped mirror mounted on a heavy iron frame and supported on a stand. The mirror can be rotated by a crank handle that connects to the mirror via a pair of gears. There is some brown paper apparently stuck to one face of the mirror.
Accession Number: 2009.ph.264
Primary Materials: Metal, Glass, Wood
Dimensions (cm): Length=38cm, Width=23cm, Height=40.5
This rotating mirror is intended to be used with manometric organ pipes in which a flame flickers in response to sound. The mirror, when turned, enables a viewer to perceive and compare modulations in the flame that would otherwise be invisible to the naked eye.
The system is described in “Altered Sensations” by David Pantalony (New York: Springer, 2009):
“Both pipes rested vertically in a wind-chest and each had a capsule attached to the middle of the pipe. Each capsule had a rubber gas input tube and an output tube that connected to a stand for the burners, which were placed one on top of the other. A rotating mirror sat adjacent to the stand in order to pick up the signal from the burners. Two ut3 pipes, for example, displayed identical flame signals. Other combinations demonstrated the differences between octaves, thirds, fifths, etc.” (pg 319).
Good: All four mirrors are intact, although somewhat clouded. The mirror still rotates. There is brown, stained paper stuck on one face of the mirror, perhaps as an attempt to protect the mirrors. The metal of the frame holding the mirror and of the stand is corroded in parts, particularly on one foot.
Manufacturer: Rudolph Koenig, Paris
Date of Manufacture: c. 1880
This mirror is part of a collection of acoustic teaching apparatus purchased from Rudolph Koenig by University of Toronto professor of physics James Loudon. It was probably purchased as a set along with manometric pipes, bunsen burners, a windchest and a stand (some of which are labelled “215” referring to the set’s entry in Koenig’s 1873 catalogue), and was likely part of Loudon’s initial 1878 purchase, and form part of a comprehensive selection of organ pipes “representing a… demonstration of every possible organ pipe effect.” (Pantalony, Altered Sensations. New York: Springer, 2009. Pg 119-122). It was likely used by students for investigations of acoustical properties at the university’s physics department teaching laboratory.
The windchest, a gas stand, and five pipes that were apparently purchased as a set with this rotating mirror (many carry the Koenig catalogue number “215”, referring to the 1873 set) have been accessioned separately.
See also, “Altered Sensations” by David Pantalony (New York: Springer, 2009) pgs 317-320.
For an example of the visualisation of a flame in a rotating mirror: https://www.youtube.com/watch?v=OHdL-65dkkY [Accessed: 10/09/2016]