ON SENSITIVE FLAMES. 
By W. F. BARRETT, 
Lecturer on Natural Science at the International College. 
S ENSITIVE flames, as they have appropriately been called, 
are flames which, by their sudden movement at the slight- 
est sound, evince a wondrous susceptibility to the influence of 
sonorous vibrations. The story of their discovery is briefly this. 
In the year 1865, whilst engaged in the preparation of the ex- 
periments for the Christmas lectures at the Royal Institution, 
the writer of this article observed that a shrill and prolonged 
sound had a curious effect on a tall and slender gas-flame which 
happened to be burning near. Under the influence of the sound 
the flame, which was about 14 inches long, shortened itself 
several inches ; at the same time the upper part spread out side- 
ways into a flat flame, which gave an increased amount of light 
from the more perfect combustion of the gas. Less strongly, 
the same effect took place when a high note was uttered or 
played even so far off as 30 or 40 feet away. So strange an 
occurrence could not be permitted to pass without further 
investigation; as soon as possible, therefore, I submitted the 
observation to a brief examination, in which I succeeded in 
finding some of the conditions of success of this singular phe- 
nomenon, and so exalting the action that the flame moved at 
every noise. The results of this inquiry I showed to Professor 
Tyndall in the early part of last year, and did not then make 
any further publication of the matter. 
I next sought to ascertain if the effect had been previously 
noticed, but could discover no published account of a similar 
experiment. I learnt, however, that mechanics sometimes 
observe the large bat’s-wing gas-flames in their workshops to 
become disturbed, and throw out little tongues of flame, when 
the noise of their work happens to be sustained and shrill. I 
next heard, through Professor Tyndall, that an American gentle- 
man, Dr. Leconte, had noticed and published an account of an 
analogous effect to this last, but not until recently did I read 
the following extract from his paper on the subject. After re- 
