Keely
"That tuning forks can be so constructed as to show coincident or concordant association with each other, is but a very weak illustration of the fact which governs pure acoustic assimilation. The best only approach a condition of about a fortieth, as regards pure attractive and propulsive receptiveness. By differentiating them to concordant thirds, they induce a condition of molecular bombardment between themselves, by alternate changes of long and short waves of sympathy. Bells rung in vacuo liberate the same number of corpuscles, at the same velocity as those surrounded by a normal atmosphere, and hence the same acoustic force attending them, but are inaudible from the fact that, in vacuo, the molecular volume is reduced. Every gaseous molecule is a resonator of itself, and is sensitive to any and all sounds induced, whether accordant or discordant." [attractive and propulsive receptiveness] [Snell Manuscript - The Book, GRADUATION OF MACHINES, page 5]
Ramsay
Musical sounds are usually caused in the ear by certain vibrations of the surrounding air, which originate from solid bodies in a state of vibration from some force exerted upon them. Vibrations of the air require to attain a certain rate of speed before they become audible to the human ear; and they require to have certain ratios of rate of rapidity in order to constitute that beautiful host of sounds which constitutes the music of mankind. These musical vibrations may arise in the air from a vibrating organ pipe, or a vibrating tuning fork, or a bell, or a sounding glass, or a strand of wire or gut-string, or other rhythmically vibrating body; but to explain and define the nature of a musical vibration from the action upon it of an elastic string is to explain and define it for all. But before defining what a vibration of a string is, let us hear what others have said about it. Charles Child Spencer, Treatise on Music, p. 6, says- "It is customary in calculating the ratios of vibration of musical strings, and which answer to the waves of the atmosphere, to reckon by double vibrations, so that instead of saying there are 32 single vibrations in the lowest sound, C, writers on this branch of music say there are 16 double vibrations in this sound. This method of calculation, therefore, gives 256 vibrations for the fourth Octave C." Playfair, in his Outlines of Natural Philosophy, p. 282, says- "It is usual to reckon the vibrations of a string different from those of a pendulum; the passage from the highest point on one side to the highest point on the other is reckoned a vibration of a pendulum; the passage from the farthest distance on one side to the farthest distance on the other and back again to its first position, is the accounted a vibration of a musical string. It is properly a double vibration." Holden, in his Rational System of Music, says- "Mr. Emerson reckons the complete vibration the time in which a sounding string moves from one side to [Scientific Basis and Build of Music, page 22]