82 FKAGMENTS OF SCIENCE. 



another pulse is ready to strike it. Thus, the impulses 

 add themselves together. In the five seconds during 

 which the forks were held near each other, the vibrating 

 fork sent 1,280 waves against its neighbour and those 

 1,280 shocks, all delivered at the proper moment, all, as 

 I have said, perfectly timed, have given such strength 

 to the vibrations of the mounted fork as to render them 

 audible to all. 



Another curious illustration of the influence of 

 synchronism on musical vibrations, is this : Three small 

 gas-flames are inserted into three glass tubes of different 

 lengths. Each of these flames can be caused to emit 

 a musical note, the pitch of which is determined by 

 the length of the tube surrounding the flame. The 

 shorter the tube the higher is the pitch. The flames 

 are now silent within their respective tubes, but each 

 of them can be caused to respond to a proper note 

 sounded anywhere in this room. With an instrument 

 called a syren, a powerful musical note, of gradually 

 increasing pitch, can be produced. Beginning with a 

 low note, and ascending gradually to a higher one, we 

 finally attain the pitch of the flame in the longest tube. 

 The moment it is reached, the flame bursts into song. 

 The other flames are still silent within their tubes. 

 But by urging the instrument on to higher notes, the 

 second flame is started, and the third alone remains. 

 A still higher note starts it also. Thus, as the sound of 

 the syren rises gradually in pitch, it awakens every 

 flame in passing, by striking it with a series of waves 

 whose periods of recurrence are similar to its own. 



Now the wave-motion from the syren is in part taken 

 up by the flame which synchronises with the waves ; and 

 were these waves to impinge upon a multitude of flames, 

 instead of upon one flame only, the transference might 

 be so great as to absorb the whole of the original wave 





