W. B. Rogers on Sonorous Vibrations by Flames, etc. 241 
of vibration anterior to the action of the explosions, as otherwise 
these would fail to have the periodic character which is necessary 
for the development of the musical effect. 
The conditions under which the wick and gauze flames be- 
come sonorous point, as I think very clearly, to the source of 
these primary or determining vibrations. It will be observed 
that such flames, in order to become musical, must be placed near 
the entrance of the tube, and must be large enough to oceupy a 
considerable part of the opening. In these circumstances the 
strong upward current created by the heat causes the air to enter 
the mouth of the tube, and traverse the narrow space between it 
and the flame with sufficient force to generate a feeble musical | 
vibration of the aerial column, such as can at any time be pro- 
uced by simply blowing from below against and into the mouth 
ofthe tube. This vibration although of itself too feeble to pro- 
duce a decided sound, has the effect of periodically increasing and 
diminishing the intensity of the combustion, by conveying suc- 
cessively greater and less supplies of atmosphere to the flame. 
there arises a powerful continuous musical sound, _ ; 
According to this view, the action of the flame in producing 
. 
included air 
nd: 
action of the vibrating column, increases the intensity of the 
_ Vibrations. These again, reacting, augment the difference be- 
of a powerful musical sound. : : : ogee 
Comparing this with the explanation given In my former 
per of the cause of the musical vibration of simple jets, it will 
seen that while in the latter case the primary source of the 
Vibration is viewed as inherent in the jet itself, in the present 
instance it is referred to the column of air m the tube, but in either 
Case it is the explosive action W ich strengthens the Siar 
as to produce the decided audible effect. It rig ~ i- 
at simple jet flames, when of large volume are to sone cs 
_ 8 acting in part like flames of wick, creating an ce Seegt : 
and thence a vibratory movement of the air column which com- 
__ bines with the primary vibration of the jet to produce the result 
ing sound, 
