Drawing the Vibrations of Sound

Through the construction of a simple apparatus, consisting of two pendulums -which oscillate at the same time-it is possible to graphically reproduce Lissajous' experiments on the commuting vibrations of the diapasons. This equipment was first built by Samuel Charles Tisley (London 1829-Unknown), under the name of harmonographer. Similar apparatuses were produced in the nineteenth century and subsequently, a list-limited to the first nineteenth-century phase-is proposed in the contribution that illustrates the essential characteristics of the harmonograph. Born as a means of analysing vibrations-but which, by its principle belongs to mechanics, for its applications to acoustic science and geometry for the ability to draw a wide variety of "harmonious" curves, which in the paper are referred to as Lissajous curves "damped".