My largest glass is G, a little below the reach of a common voice, and my highest G, including three compleat octaves.—To distinguish the glasses the more readily to the eye, I have painted the apparent parts of the glasses within side, every semitone white, and the other notes of the octave with the seven prismatic colours, viz. C, red; D, orange; E, yellow; F, green; G, blue; A, indigo; B, purple; and C, red again;—so that glasses of the same colour (the white excepted) are always octaves to each other.
This instrument is played upon, by sitting before the middle of the set of glasses as before the keys of a harpsichord, turning them with the foot, and wetting them now and then with a spunge and clean water. The fingers should be first a little soaked in water, and quite free from all greasiness; a little fine chalk upon them is sometimes useful, to make them catch the glass and bring out the tone more readily. Both hands are used, by which means different parts are played together.—Observe, that the tones are best drawn out when the glasses turn from the ends of the fingers, not when they turn to them.
The advantages of this instrument are, that its tones are incomparably sweet beyond those of any other; that they may be swelled and softened at pleasure by stronger or weaker pressures of the finger, and continued to any length; and that the instrument, being once well tuned, never again wants tuning.
In honour of your musical language, I have borrowed from it the name of this instrument, calling it the Armonica.
With great esteem and respect, I am, &c.
B. FRANKLIN.
TO A FRIEND[63].
[Respecting the best Mediums for conveying Sound.]
July 20, 1762.