By _mode of propagation_ I mean the organs brought into use for the purpose of producing the sound, the apertures through which the sound force passes, and the auxiliaries by which it is moulded into certain shapes. By _ultimate form_ I mean the geometrical shape of the sound force when first converted into sound. That there is such a thing as form has been clearly demonstrated by the phoneidoscope. Prof. John B. De Mott has very kindly aided me in reducing certain sounds to a visible condition. I had conceived an idea before this that if the path described by the energy which produced sound could be made visible, that it would be found to have the form of a convolute spiral, that these spirals recede from the centre or point of propagation in every direction like the radii of a sphere, and that that aspect of sound which we call waves, is simply the point at which these spirals intercept each other, which of necessity would be of uniform distance from the centre, increasing at each successive point throughout the entire sound-sphere or space through which the sound passes in all directions from the centre to infinity. I shall refrain from discussing this point till such a time as I can show at greater length my reasons for this belief. I may add here that I have made records of the human voice with which I have deceived the monkeys, and I have made records of the monkey's voice with which I have deceived the very elect of linguists and musicians. Some critic once remarked to me that the sound made by a monkey was not really laughter, but only a kind of good-natured growling. This may be correct, but the same is true of human laughter, as the one may be converted into the other, and a good-natured growl expresses the emotion which is felt by man as well as monkey. The phonograph shows that they are identical in sound and form, besides the fact that they are the outburst of the same passion, actuated by the same cause and executed by the same muscles, so that their identity, mentally, physically, and mechanically, is the same. [Sidenote: VOWEL SOUNDS]