244 ANNUAL OF SCIENTIFIC DISCOVERY. 



my great surprise, instantly started into song. Placing the finger on the end 

 of the tube, and silencing the melody, on repeating the experiment, the same 

 result was obtained. 



I placed the syrene near the flame, as before. The latter was burning 

 tranquilly within its tube. Ascending gradually from the lowest notes of the 

 instrument, at the moment when the soiind of the syrene reached the pitch 

 of the tube which surrounded the gas flame, the latter suddenly stretched 

 itself and commenced its song, which continued indefinitely after the syrene 

 had ceased to sound. 



With the jet which I have described, and a glass tube, twelve inches long, 

 and from one-half to three-fourths of an inch internal diameter, this result 

 can be obtained with ease and certainty. If the voice be thrown a little 

 higher or lower than the note due to the tube, no visible effect is produced 

 upon the flame : the pitch of the voice must lie within the region of the aud- 

 ible beats. 



By varying the length of the tube we vary the note produced, and the 

 voice must be modified accordingly. 



That the shaking of the flame, to which I have already referred, proceeds 

 in exact accordance with the beats, is beautifully shown by a tuning-fork 

 which gives the same note as the flame. Loading the fork so as to throw it 

 slightly out of unison with the flame, when the former is sounded and brought 

 near the flame, the jum pings are seen at exactly the same intervals as those 

 in which the beats are heard. When the tuning-fork is brought over a reson- 

 ant jar or bottle, the beats maybe heard and the jumpings seen by a thousand 

 people at once. By changing the load upon the tuning-fork, or by slightly 

 altering the size of the flame, the quickness with which the beats succeed each 

 other may be changed, but in all cases the jumpings address the eye at the 

 same moment that the beats address the ear. 



With the tuning-fork I have obtained the same results as with the voice and 

 syrene. Holding a fork over a tube which responds to it, and which con- 

 tains within it a silent flame of gas, the latter immediately starts into song. 

 I have obtained this result with a series of tubes varying from ten and a half 

 to twenty-nine inches in length. The following experiment could be made. 

 A series of tubes, capable of producing the notes of the gamut, might be 

 placed over suitable jets of gas ; all being silent, let the gamut be run over 

 by a musician with an instrument sufficiently powerful, placed at a distance 

 of twenty or thirty yards. At the sound of each particular note, the gas-jet 

 contained in the corresponding tube would instantly start into song. 



I must remark, however, that with the jet which I have used, the experi- 

 ment is most easily made with a tube about eleven or twelve inches long j 

 with longer tubes it is more difficult to prevent the flame from singing 

 spontaneously, that is, without external excitation. 



The principal point to be attended to is this. With a tube, say of twelve 

 inches in length, the flame requires to occupy a certain position in the tube 

 in order that it shall sing with a, maximum intensity. Let the tube be 

 raised, so that the flame may penetrate it to a less extent ; the energy of the 

 sound will be thereby diminished, and a point (A), will at length be attained 



