96 Prof. Tyndall on Sounding and Sensitive Flames, 



strike an anvil ; the flame remains steady and without response. 

 I urge against the broad face of the flame a stream of air from 

 the blowpipe just employed. The flame is cut in two by the 

 stream of air; it flutters slightly; and now when the whistle 

 is sounded the flame instantly starts. A knock on the table 

 causes the two half-flames to unite and form for an instant a 

 flame of the ordinary shape. By a slight variation of the ex- 

 periment, the two side flames disappear when the whistle is 

 sounded, and a central tongue of flame is thrust forth in their 

 stead. 



Passing from a fish-tail to a bat's-wing burner, I obtain this 

 broad steady flame. It is quite insensible to the loudest sound 

 which would be tolerable here. The flame is fed from this gas- 

 holder, which places a power of pressure at my disposal unattain- 

 able from the gas-pipes of the Institution. I turn on more gas ; 

 the flame enlarges, but it is still insensible to sound. I enlarge it 

 still more, and now a slight flutter of its edge answers to the 

 sound of the whistle. Turning on a little more gas, and sound- 

 ing again, the jumping of the flame is still more distinct. 

 Finally I turn on gas until the flame is on the point of roaring, 

 as flames do when the pressure is too great. I now sound my 

 whistle; the flame roars and thrusts suddenly upwards eight 

 long quivering tongues. 



1 strike this distant anvil with a hammer, the flame instantly 

 responds by thrusting forth its tongues. 



Another flame is now before you. It issues from a burner 

 formed of ordinary gas-tubing by my assistant. The flame is 

 18 inches long, and smokes copiously. I sound the whistle; 

 the flame falls to a height of 9 inches, the smoke disappears, 

 and the brilliancy of the flame is augmented *. 



Here are two other flames, also issuing from burners formed 

 by my assistant. The one of them is long, straight, and 

 smoky ; the other is short, forked, and brilliant. I sound the 

 whistle; the long flame becomes short, forked, and brilliant; 

 the forked flame becomes long and smoky. As regards, there- 

 fore, their response to the sonorous waves, the one of these flames 

 is the exact complement of the other. 



Here are various flat flames, 10 inches high, and about 

 3 inches across at their widest part. They are purposely made 

 forked flames. When the whistle sounds, the plane of each 

 flame turns ninety degrees round, and continues in its new po- 

 sition as long as the whistle continues to sound. 



Here, again, is a flame of admirable steadiness and brilliancy, 



* Mr. Barrett also observed the increase of light on the shortening 

 of a flame by a musical sound ; nor did the superior effect of high notes 

 escape the attention of this acute and skilful young experimenter. 



