v.] SYMPATHETIC VIBRATION. 61 



This principle may be illustrated in another and very striking 

 manner by means of two large tuning-forks mounted on sound- 

 ing-boxes and tuned to exact unison. One of the forks is set 

 in active vibration by means of a fiddle-bow, and then brought 

 near to the other one, the open mouths of the two sounding- 

 boxes being presented to each other to make the effect as great 

 as possible. 



After a few moments, if the fork originally sounded is damped 

 to stop its sound, it will be found that the other fork has taken 

 up the vibration and is sounding, not so loudly as the original 

 fork was, but still distinctly. If the two forks are not in unison, 

 no amount of bowing of the one will have the slightest effect 

 in producing sound from the other. 



Again, suppose we have a long room, and a fiddle at one 

 end of it, and that between it and an observer at the other end 

 of the room there is a screen of fiddles, all tuned like the solitary 

 one, we can imagine that in that case the observer would 

 scarcely hear the note produced upon any one of the open 

 strings of the solitary fiddle. Why ? The reason is that the 

 air-pulses set up by the open strings of this fiddle, in unison 

 with all the other fiddles, would set all the other open strings 

 in vibration, and upon the principle that you cannot eat your 

 cake and save it too, the air-pulses set in motion by the vibration 

 of the fiddle cannot set all those strings vibrating and still pass 

 on to one's ear at the other end of the room as if nothing 

 had happened. 



The work, in fact, which the air, the medium in this case, 



pots, or the like of the same bignesse ; the one being full, the other empty, 

 shall, stricken, be a just Diapason in sonnd one to the other : or that there should 

 be such sympathy in sounds, that two Lutes of equal size being laid upon a 

 Table, and tuned unison, or alike in the Gamma, G, sol, re, ut, or any other 

 string ; the one stricken, the other untouched shall answer it?" The Compleat 

 Gentleman Fashioning him dbsolut in the most necessary and commendable 

 Qualities concerning Minde or Body, that may be required in a Noble Gentleman. 

 By Henry Peacham, M.A., Sometime of Trinitic Colledge in Cambridge. Third 

 edition, 1661. 



