506 The Velocity of Light . [September, 
This solar aqueous disturbance is regulated in its more 
and less by the 778 times the 347 centimetres are annually 
renewed ; we have— 
(396 m. — 347 m.) 4 - 778 = 6*58 metres, 
as mean acceleration and retardation of sound, and of the 
atmosphere through its whole height by wind. It is — 
347 m.-5i m. : 347 m. + 51 m. = 1 : 1*37 
as the oscillations of the magnetic needle within the mean 
of the two regions of intensity, the mean of the minima to 
that of the maxima of magnetic intensity being 1 : 1*37 2 . 
The apparent irregularities in this system of compensa- 
tions corresponding to 1 -r 59*56, the eccentricity of the 
orbit of the earth, or the mean tension of all ascending 
vapour against the weight of the atmosphere, or to— 
1 59*56 2 = 1 4-3546 
the mass of the sea to that of the earth, &c. 
The compressibility of water at 15*22° C. by one atmo- 
sphere being 0*0000464, the velocity of sound in water is, 
according to Laplace’s ^g 4 -A, equal 1454 metres. 
The earth below the atmosphere and sea is a solid, with 
an intervenient more or less liquid stratum, in the mean 
5*45 times more dense than the salt sea. Attraction within 
changes with distribution of density and depth. The 
change in solar distance is — 
1 4- 2978 ; it is ^2978 = 5*45 : 
when we assume as probable that the mean of compressi- 
bility of the substances composing the earth is under 
pressure of one atmosphere 1 4 - 29*78 of that of water, con- 
sidering differences of temperature, 0. s. p. as 1 4* 29*78, is 
the percentage of water-stuff in the air or of salt in the 
sea, the velocity of sound for the mean earth will be 5*45 
times that in water, 0^1454 m. x 5*45 = 7933 metres. 
The velocity of a point at the equator in daily rotation is 
457 metres, and its centrifugality is 1—289 of gravity. A 
tangential velocity of 457 m. x ^289 = 7933 metres, or that 
of sound in the mean solid would make any particle all over 
the earth absolutely centrifugal if the pressure of the atmo- 
sphere and sea, and adhesion and cohesion of molecules in 
and amongst each other, the centrifugal opposition and the 
co-attraCtion of the sun, o. s. p., did not turn projection into 
