REFLECTION OF SOUND. 43 



appropriate musical sound that gas is utterly broken up, and the 

 flame which would burn silently without the action of the musical 

 vibration at a height of two feet, will fall suddenly and break up 

 and roar at a height of only eight or nine inches. Here is a flame 

 issuing from a nipple such as I have described. The pressure is so 

 arranged as to bring it near the point of flaring, and a very slight 

 action of an appropriate sound upon the flame will bring it down, 

 abolishing the light altogether. Thus, when I take this bunch of 

 keys and shake them, the noise of the keys brings the flame down. 

 In such a flame we have a re-agent of extraordinary delicacy as 

 regards musical vibrations. We are indebted for the discovery of 

 this action of sound upon flame to one of the most remarkable men 

 in the United States, a man whom I am sorry to say was cut off 

 by the war from active work in science for some time, but he is 

 now engaged upon it again ; I mean Professor John Le Comte. He 

 observed this action of sound, and, moreover, he gave us the distinct 

 intimation that the flame required to be brought to the edge of flaring 

 in order to get this effect. You bring the flame to the edge of a 

 precipice as it were, and the musical sound pushes it over. Sub- 

 sequently, when I had the honour of his assistance at the Royal 

 Institution, Professor Barrett observed this effect also upon a flame, 

 and afterwards made various interesting experiments upon the subject. 

 It has also been experimented upon by Mr. Philip Barry and by my 

 present excellent assistant, and I have done something towards 

 exalting the sensitiveness of the flame myself. It is to be our 

 re-agent at the present time. Many of my continental friends who 

 desire to repeat these experiments find some difficulty in doing so, 

 because a full exposition of the proper conditions necessary to success 

 has never yet been given. Hence, my reason for introducing the 

 subject here. It is advisable to have a gas-holder that will enable 

 you to apply considerable pressure, and the gas-holder before you is 

 loaded in the manner you perceive, in order to bring the flame to the 

 required proximity to its point of flaring. It is also desirable that all 

 passages between the burner and the gas-holder should be fully open. 

 This is a point ot considerable importance. With regard to the seat 

 ot sensitiveness in this flame, the action is not caused by the im- 

 pinging of the sonorous waves upon the nipple, it is not caused by the 



