36 John LeConte—Sound-Shadows in Water. 
as long as they are in air. Hence, according to theory, if 
Colladon’s observations had been within the radius (200 meters) 
at which the musical tone of the sonorous bell was heard, 
Vnarionstes) Colladon does not inform us at what distance 
fr ating bell his observations in relation to the 
acoustical ahagover were made, so that it is seat na to apply 
this critical test of the theory of shadows. But the presump- 
tion is, that the observations were ade in the “reakbortoos 
at which dindiosl tones were transmitted, we are Agere from 
determining the wave-length by the number of vibrations. It 
~ appears that in water, grave sounds are more rapidly suppressed 
or damped than acute sounds; so that at moderate distances 
from the sonorous center, only the short and sharp sound due to 
the shock of the striking hammer was transmitted to distant 
points through che. water. It is obvious that the wave- “lengths 
of sounds of this character must be determined by other con- 
siderations than those relating to the musical pite 
In relation to i bic waves + aang by sudden blows and 
explosions,* it may be more difficult to form a just estimate of 
the wave-length ae in the case of musical sounds. Never- 
theless it is evident that the wave-length must be directly pro- 
* It may be questionable whether the elastic waves generated by momentary ex 
by setson fa ‘the y pene (hs his work on the § ‘Theory of Sound.” Vol 
ii, pp. 297-3 
Furtherm the admirable and ra aster refined arrangements devised b 
— for investigating the phenomena of sound enabled him to subm it this 
of mercury was so sudden that the wave generated Mg the air was muc oping 
and tne “coup” was muc a ear k than that which was produce 
pistol charged ees shee ge Sag __ (PP. 47-48 ; and pp. 278-281). He ads 
trés oo eS 
Again, the Ane pctis of General H. L. Abbot (U. S. Engineers), incident to 
