218 On the Construction of Buildings 
every direction, till they gradually subside and mingle in the gen- 
eral level. The movement thus produced in the water, is appa- 
rent only. It is the impulse, communicated from particle to par- 
ticle in the water of which the wave consists, not the motion of 
the water itself. Precisely analogous to this is the communica 
tion of sound in air, except that, in this latter case, as the impres- 
sion is produced in, rather than upon, the surface of an elastic 
medium, it spreads equally every way, and would form, instead 
of concentric circles, concentric spherical lamine. 
The velocity of sound, as also its intensity, varies according to 
the nature and condition of the medium through which it 1s 
transmitted. In adry atmosphere, and at the freezing tempera 
ture, sound travels at the rate of three hundred and sixty-three 
- yards, or one thousand and ninety feet in a second. For every 
additional degree of Fahrenheit this velocity is increased about 
one thousandth part. 
- In the different gases this result is found to vary considerably, 
the velocity in hydrogen being nearly three times greater, ana! 
carbonic and sulphuric acid gases much less than in common ait. 
Through liquids the velocity is greatly increased, moving 1n Wa 
ter, at the temperature of 46° 6’ Fahrenheit, at the rate of four 
thousand seven hundred and eight feet per second. 
The propagation or conduction of sound through solid bodies, 
presents many interesting points of consideration. Solids af 
good conductors in proportion to their hardness and elasticity; — 
he conv 
ance of sound along the cast iron pipes of Paris, instituted by 
According to Chladni, the relative velocities of sound in dif- 
fere i , : 
nt solids are as in the following table: cy in tnt, poeta 
Tin, - 1" in - * 7,80 
Silver, __ - » eR ane 9,300 
Dbrass, - “ - - - ,800 
Baked clay, * a 10,000 to 12,000 
Copper, Ke - 12,500 
Glass, . és Z ~ 17,500 
Tron,* - 
| i : 2; AT BOU ee 
Wopdi.gh xatious Kinds,, >... 11,000.to ABT 
* It will be seen there is a t discrepancy between the result in 1rop on the 
stated, and that obtained by aaepainertn: of Biot. Hersche peerves tet 
error in this case throws a doubt on all the rest; unless, teel 
—Eneye. Metropol, Art. Sound. 
