Vibrations on Gaseous and Liquid Jets. 



379 



Mr. Barrett, late laboratory assistant in this place, first ob- 

 served the shortening of a tall flame issuing from the single 

 orifice of this burner when the higher notes of a circular plate 

 were sounded ; and, by the selection of more suitable burners, 

 he afterwards succeeded in rendering the flame extremely sen- 

 sitive*. Observing the precaution above adverted to, we can 

 readily obtain in an exalted degree the shortening of the flame. 

 It is now before you, being 18 inches long and smoking copi- 

 ously. When I sound the whistle the flame falls to a height of 

 9 inches, the smoke disappearing, and the flame increasing in 

 brightness. 



A long flame may be shortened and a short one lengthened, 

 according to circumstances, by these sonorous vibrations. Here, 

 for example, are two flames issuing from rough burners formed 

 from pewter tubing. The one flame (fig. 7) is long, straight, 

 and smoky; the other (fig. 8) is short, forked, and brilliant. 

 On sounding the whistle, the long flame becomes short, forked 

 and brilliant, as in fig. 9 ; the forked flame becomes long and 

 smoky, as in fig. 10. As regards, therefore, their response to the 

 sound of the whistle, one of these flames is the complement of the 

 other. 



Fig. 10. Fig. 11. Fig. 12. 



* For Mr. Barrett's own account of his experiments I refer the reader 

 to the Philosophical Magazine for March 1867. 



