482 Scientific Intelligence. 
If we take two organ pipes in unison, attach to them two flames, 
and sound one of them, the flame of the other will show that the 
incInded column of air has had the vibrations communicated to it, 
and that this communication continues even when the organ pipes 
observed in the inset "Tf we now sou id the second pipe cole, 
and thus induce vibrations of its own, these will combine with 
the resonance vibrations, and the flame violently indicates beats 
which can also be distinctly hear 
I draw particular attention to thie isolated appearance of reson- 
ance vibrations in the column of air, because this does not happen 
in the case of two violin strings stretched over the same sounding 
board, where the string vibrations are always combined with 
the resonance vibrations in the influenced string, even if it is not 
sounded. The beats produced by two such strings acting on 
each other are of such nature that one reaches the maximum 
amplitude while the other is at re minimum, The flames of two 
organ pipes show the same phenomenon, one rising while the other 
falls. In the latter both must et while it is necessary to 
sound poly one of the strings. 
In pipes of perfect unison whose vibrations make the same mu- 
flame, the flame will, in the case of ines , be more violently agi- 
tated than the two flames 8 were; for in the latter case they were 
— both by direct and by induced vibrations, which in the same 
column of air were of very unequal intensity ; nore however, two 
notes of almost equal intensity are produced directly in two equa 
columns of air. If the two notes are made gradually to approach 
unison we shall observe that we cannot retard at will the beats as 
ace suddenly ce two columns of air vibrate like 4 
system, that is, like two mlebinarid tuned bodies which are so intl- 
mately connected, a each other so strongly, that neither 
can emit its gveung note; the seclgiacee being that but a single 
note, a mean between the two, is This note is stron 
than that of a single organ pipe and causes the flame to contract 
in the center, an above a non-luminous blue broad ba 
As we approach pure unison the height of this dark base increases, 
the luminous contraction disappears and when unison is reache 
the flame appears at rest. At the same time the strong funda- 
‘mental note of the organ pipes has almost entirely disa ppeared,, 
