168 ANNUAL OF SCIENTIFIC DISCOVERY. 



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. The one 

 of them is loilg, 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, therefore, 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 90 de- 

 grees around, and continues in its new position as long as the 

 whistle continues to sound. Here, again, is a flame of admirable 

 steadiness and brilliancy, issuing from a single circular orifice in 

 a common iron nipple. I whistle, clap my hands, strike the an- 

 vil, and produce other sounds: the flame is perfectly steady. 

 Observe the gradual change from this apathy to sensitiveness. 

 The flame is now 4 inches high. I make its height 6 inches; it is 

 still indifferent. I make it 10 inches ; a barely perceptible quiver 

 responds to the whistle. I make it 14 inches high ; and now it 

 jumps briskly the moment the anvil is tapped or the whistle 

 sounded. I augment the pressure ; the flame is now 16 inches 

 long, and you observe a quivering which announces that the flame 

 is near roaring. I increase the pressure ; it now roars and short- 

 ejis at the same time to a height of 8 inches. I diminish the pres- 

 sure a little ; the flame is again 16 inches long, but it is on the 

 point of roaring. It stands as it were on the brink of a precipice. 

 The whistle pushes it over. Observe it shortens when the whistle 

 sounds, exactly as it did when the pressure was in excess. The 

 sonorous pulses, in fact, furnish the supplement of energy neces- 

 sary to produce the roar and shorten the flame. This is the sim- 

 ple philosophy of all these sensitive flames. 



*' Here, again, is an inverted bell, which I cause to sound by 

 means of a fiddle-bow, producing a powerful tone. The flame is 

 unmoved. I bring a half-penny into contact with the surface of 

 the bell ; the consequent rattle contains the high notes to which 

 the flame is sensitive. It instantly shortens, flutters, and roars, 

 when the coin touches the bell. Here is another flame 20 inches 

 long. I take this fiddle in my hand, and pass a bow over the three 

 strings which emit the deepest notes. There is no response on the 

 part of the flame. I sound the highest string; the jet instantly 

 squats down to a tumultuous, bushy flame, 8 inches long. Some 

 of these flames are of marvellous sensibility ; one such is at pres- 

 ent burning before you. It is nearly 20 inches long; but the 

 slightest tap on a distant anvil knocks it down to 8 inches. I 

 shake this bunch of keys or these few copper coins in my hand ; 

 the flame responds to every tinkle. I may stand at a distance of 

 20 yards from this flame ; the dropping of a sixpence from a 

 height of a couple of inches into a hand already containing coin 

 knocks the flame down. I cannot walk across the floor without 

 affecting the flame. The creaking of my boots sets it in violent 

 commotion. The crumpling of a bit of paper, or the rustle of a 



