24 On the Sounds produced by Flame in Tubes. [1818. 



trance of the tube an additional effect of the same kind is pro- 

 duced, by the edge obstructing the air which passes near it; 

 the air is therefore propelled on to the flame, and mingling 

 with the inflammable matter existing there, forms portions 

 of exploding mixtures, which are fired by the contiguous 

 burning parts, and produce sound, in the manner already 

 described, with a roaring flame ; only, the impelled current 

 being more uniform, and the detonations taking place more 

 rapidly and regularly, and in smaller quantities, the sound 

 becomes continuous and musical, and is rendered still more so 

 by the effect of the tube in forming an echo. 



That the roaring flame gives sound in consequence of ex- 

 plosion, can hardly be doubted ; and the progress from a roar 

 to a musical tone is easily shown in the following manner: 

 Take a lamp with a common cotton wick, and trim it with aether 

 or alcohol ; light it, and hold a tube over the flame (that which 

 I have used is a thin tube of glass about an inch in diameter, 

 and nearly 30 inches long) ; in a few seconds after introducing 

 the flame, the draught will be sufficiently strong to blow it 

 out, but if the current be obstructed by applying the fingers 

 round the lamp at the bottom of the tube, combustion will go 

 on, though irregularly ; then, by a little management in ad- 

 mitting the air on one side or the other, and in greater or 

 lesser quantity, it may be impelled on to the flame in various 

 degrees, so as to produce a rough roaring sound, or one more 

 continued and uniform, of a higher note, and more musical ; 

 and these may be made to pass into each other at pleasure : 

 then, by substituting a stream of aethereal vapour for the wick, 

 which may be easily done from a small flask through a tube, 

 the tones may be brought out more and more clearly, until 

 they exactly resemble those of hydrogen. 



A similar experiment may be made with coal-gas : light a 

 small Argand burner with a low flame, and bring a glass tube, 

 which is very little larger than the diameter of the flame, 

 down upon it so as nearly to include it : the current of air will 

 be impelled on the external part of the flame, it will remove 

 the limit of combustion a little way up from the burner, that 

 part of the flame will vibrate rapidly, burning with continued 

 explosions, and an irregular tone will be obtained. Remove 

 the burner, and fix on a long slender pipe to the gas-tube, so 



