At a meeting of the Philosophical Society, held April 5th, 1878, I described the results of some examinations of the tin foil whioh had been indented by the stylus, or needle point, of the phonograph.
My object was to ascertain the shapes of the indentations made by different known sounds. For this purpose, Dr. Plush, the superintendent of the Philadelphia Local Telegraph Co, kindly offered his assistance. The vowels and diphthongs were spoken into the mouthpiece of the apparatus with small panels in the order seen on the diagram.
These sounds were repeated thrice on each of three foils. They were then mounted on glass plates, separated, and labeled. Finally, at the suggestion of Mr. Knight, they were cut out and mounted on another piece of glass vertically, instead of horizontally, in order that a number of the dents produced by any given sound might be on the screen at once. I am much indebted to Mr. Holman for his kindness in adapting the apparatus, which he himself will explain a little later to the purpose of showing these phonographic records.
Lissajous, Leon Scott and KSn~g have provided the means of transforming sounds into form, in various ways, viz. : By bright points on the ends of steel bars of different thicknesses; by vibrating membranes at the extremity of a ,, phonautograph," and by flames reflected in a rotating mirror. It was natural to conclude that the same vibrations, imparted to a steel point by means of a metal diaphragm, would leave an equally characteristic trace.
It was intended to take a solid cast of these depressions in Canada balsam, or some other transparent substance, and then reproduce, in the mind's eye, the path of the stylus point. There has not been time for this.
The same voice (that of Dr. Plush), speaking the following vowels and diphthongs as nearly as possible at the same distance from the mouthpiece, was relied upon for the matrices.