|Description||Overlapping spiral curves showing interference patterns made by a twin elliptic pendulum harmonograph, a mechanical device invented by Joseph Goold. |
Figure accompanying a printed description headed 'Sound-Curve Tracings' by Joseph Goold, Stratford House, Nottingham. This three-page pamphlet was collected with an envelope containing three specimens of harmonograph outputs, of which this is one.
Joseph Goold was not a Fellow of the Royal Society. He contributed to the book Harmonic vibration and vibration figures by Joseph Goold, Charles E. Benham, Richard Kerr and L.R. Wilberforce (1909) and was noticed in Annie Besant's Thought-forms (1901). His harmonograph was exhibited at a Royal Society soirees in 1894 and 1896.