Vibrations on Gaseous and Liquid Jets. 



385 



But when a certain pipe, which stands about the middle of the 

 series, is sounded, the smoke-column drops, forming a short 

 stem with a thick, bushy head. It is also pressed down, as 

 by a vertical wind, by a knock upon the table. At every tap 

 it falls. A stroke on an anvil, on the contrary, produces little 

 or no effect. In fact, the notes here effective are of a much 

 lower pitch than those which were most efficient in the case of 

 the flames. 



The amount of shrinkage exhibited by some of these smoke- 

 columns, in proportion to their length, is far greater than that 

 of the flames. A tap on the table causes a smoke-jet eighteen 

 inches high to shorten to a bushy bouquet with a stem not 

 more than an inch in height. The smoke-column, moreover, 

 responds to the voice ; a cough knocks it down : and it dances 

 to the tune of a musical box. Some notes cause the mere top 

 of the smoke-column to gather itself up into a bouquet; at 

 other notes the bouquet is formed midway down ; while notes of 

 more suitable pitch cause the column to contract itself to a 

 cumulus not more than an inch above the end of the burner. 

 As the music continues, the action of the smoke-column consists 

 of a series of rapid leaps from one of these forms to another*. 

 Various forms of the dancing jet are shown in fig. 16. 



In perfectly still air these Fig. 16. 



slender smoke-columns rise 

 sometimes to a height of two 

 feet, apparently vanishing 

 into air at their summits. 

 Even the most sensitive flame 

 then falls far behind them in 

 delicacy ; and though less 

 striking, the smoke wreaths 

 are often more graceful than 

 the flames. Every word and 

 every syllable, for example, 

 of the foregoing stanza from 

 Spenser tumbles such a 

 smoke-jet into confusion. 

 To produce such effects a 

 perfectly tranquil atmosphere 

 is necessary. Elame-experi- A 

 ments are possible in an 

 atmosphere where smoke-jets are utterly unmanageable. 



[These experiments on smoke-jets were commenced nearly a 

 year ago. Their execution was entrusted to Mr. Barrett, from 



* Could the jets of unignited gas be seen without any admixture of 

 smoke, their sensitiveness, I doubt not, might be increased. 



Phil Mag. S. 4. Vol. 33. No. 224. May 1867. 2 C 



