Object, Instrument, Technology

In 1868, Henri-Victor Régnault described an apparatus for determining the speed of sound, capable of accurately measuring time intervals to fractions of a second.

Object, Instrument, Technology

The Fourier analyzer, which was called by Rudolph Koenig an “Analyzer of the timbre of sounds”, is a large device (about 36 inches tall) for simultaneously observing several components of a sound.

Object, Instrument, Technology

A windchest is a wooden box that holds air to be delivered to organ pipes, which are inserted in valved holes. These two examples were used in lectures to demonstrate the different characteristics of organ pipes of varying sizes and shapes.

Object, Instrument, Technology

The Case Collection of Physics Instruments (CCPI) has several dozen forks mounted on resonance boxes (see Fig. 1).

Object, Instrument, Technology

A tonometer consists of a series of steel cylinders that resonate at specific frequencies upon being struck with a metal hammer. They are used as standards for high frequencies, in the same manner as tuning forks. The transverse vibrational frequencies (i.e. fundamental and harmonics) of a given cylinder depend on the length, elastic modulus, and linear density of the metal.

Object, Instrument, Technology

The fork-clock was first described by N. Niaudet in 1866. It is used to determine the frequency of a fork to high accuracy. The vibrating fork drives the clock in the same way as a pendulum in a pendulum clock–by way of an escapement mechanism. This Max Kohl clock uses a 100 Hz fork to drive a tiny escapement. Energy is provided by an enclosed wind-up spring. The three dials record the total number of vibrations. The absolute frequency of the fork can then be determined by comparison with an astronomical time standard.

Object, Instrument, Technology

The double siren is an instrument that produces sounds from two sources in a way that allows the phase of one sound to be changed relative to that of the other. It is capable of producing everything in the range of a half-tone to an octave. A double siren consists of two coaxial Dove sirens—disks rotating at high speed. As air flows through a series of holes in each disk, a distinct tone is produced, the frequency of which depends on the rotational speed of the disk, and the spacing of the holes in the disk.

Object, Instrument, Technology

Invented by John Shore in 1711, the tuning fork was initially used by musicians. After Chladni’s studies of its vibrations, however, it was also extensively employed by acousticians, who praised the purity of its sound. Hermann von Helmholtz, especially, based his experiments with beats, combination tones, and simple tones on tuning forks attached to resonators that enhanced their suitability for experimentation.

Object, Instrument, Technology

(The following description is from a “Description of Appunn’s Tonnemeters,” by Alexander J. Ellis, F.R.S., &c.; MS in the Western Galleries of the South Kensington Museum, 1880. With the tonometers. Science Museum technical file T/1876-466. The note was written by Alexander J.

Object, Instrument, Technology

This set of 3 tuning forks, each mounted on its’ own resonator box, was made in Paris between about 1870 and 1900. The tuning forks were each milled from a single blank of fine steel and were then precisely tuned to produce a single, specific, tone. The resonator boxes that they are bolted to are wood, made from the same spruce often used in stringed musical instruments. Spruce wood is naturally responsive to sound vibrations and is the ideal material for this application.