XLVI
such bodies are, the better will they transport sound. A highly
interesting phenomenon is Marloye's Diapason, consisting of
two tuning-forks, which are screwed on two hollow boxes made
of very thin wood and open at one side. If one of these tun
ing-forks is struck, the other one will sound too, even at a di
stance of 10–12' and will vibrate self-dependent after the sound
of the first fork has been stopped.— Such vibrating bodies even
strengthen sound, and this is called Resonance (see following
passage and 253).
2) The production of Musical sounds.
§ 108. Difference of sound and noise. 242. Limit of per
ceptible sounds; musical scale; intervals and the numbers of
vibrations, by which they are produced.
§ 109. By different apparatus (Savart's Monochord, the
Siren of Cagniard de la Tour, the cogged wheel, each tooth strik
ing a card whilst passing, Stewart's Primer, page 59. 60) the fol
lowing law may be affirmed. The pitch of a sound depends
on the number of vibrations produced in one second. Equal
sounds are produced by one and the same number of vibrations
whatever may be the source of the sound. The quotient of 1100
ft. and the number of vibrations shows the length of one sound
wave. Hence we also may say, that the pitch of a sound de
pends on the length of the sound-waves.
§ 110. The names of the 8 tones of the musical scale are:
do, re, mi, fa, sol, la, sa or si: The tone produced by one half
of the string or by the double number of sound-vibrations is call
ed the octave. The corresponding lengths of the string for the
8 tones from the key-note to the octave are: 1, 8/9, 4/5, ¾, ⅔, 3/5, 8/15,
½, and the corresponding numbers of vibrations: 1, 9/8, 5/4, 4/3, 3/2,
5/3, 15/8, 2. Harmony and Dissonance, see: 256.
§ 111. The tuning-fork and Resonance of air, see: 253.
