The permanent record obtained with Mr T. A. Edison's phonograph has afforded a new opportunity of investigating the nature of spoken sounds, and the method which this invention placed at our disposal appears to us to possess several important advantages.

This method consists in obtaining a magnified transcript on paper of the indentations impressed by spoken vowels on the tinfoil of the phonograph, and then subjecting the periodic wave-forms thus obtained to harmonic analysis.

The curves as drawn in ink on paper represent to a large scale the surface of a longitudinal section of the tinfoil made along the centre of the furrow impressed by the pricker of the phonograph. The forms impressed on the tinfoil depend essentially on the movement which a particle of air performs when the given sound is being uttered, and the harmonic constituents of each period of the continuous wave-form indicate the relative proportions in which the prime tone and its harmonics are present in the sound.

We thus obtain what may be called a harmonic analysis of the vowel sounds.