C. K. Wead—Intensity of Sound. 177 
Art. XXII.—On the Intensity of Sound—I. The Energy and 
Coefficient of Damping of a Tuning Fork; by Cuas, K. Wnap. 
No one doubts that a sounding body is distributing energy, 
and that a sound-wave is one mode of transmitting energy ; 
but in most practical cases the quantity of energy involved is so 
small as to elude easy measurement, and the problem is sometimes 
complicated by physiological questions. Attention has been di- 
rected mainly, in acoustical measurements, to finding the velocity 
of sound in various media, and to determining the vibration- 
frequency of the notes of the scale and of sounding bodies; 
this last problem has been solved experimentally in more than 
a score of ways, from the simple rod-tonometer that was so 
body, and in deducing the equations of harmonic motion as is - 
done by Lord Rayleigh, from assuming that the sum of the 
kinetic and potential energy in the vibrating body is constant; 
ut here as before we have no numerical data given to help 
toward clear thinking, 
© may consider our subject under three heads: 
A. Instruments to which a store of energy 18 imparted ab 
Once, and which are then left to themselves; e¢. g. tuning fork, 
bell, and all stringed instruments. Be 
- Instruments that store up little or no energy, and so need 
& constant supply from outside: e. g. all wind and reed instru- 
ments, singing flames, and the voice. 
Am. Jour, Scr—Tarep Serres, VoL. XXVI, No. 15%.—Sept., 1888. 
