THE 
JOURNAL OF 
SCIENCE. 
SEPTEMBER, 1883. 
I. THE VELOCITY OF LIGHT.* 
By O. Reichenbach. 
“ Hence the agreement or disagreement of the values of V and v 
furnishes a test of the ele&ro-magnetic theory of Light.” — Clerk 
Maxwell. 
t LL mattert being equally subject to gravity, the 
variety in its distribution leading to variety of mo- 
tions can be the only cause of variety of matter. 
Laplace’s V= ^gHK-f-D gives for air, at 15*22 C., the 
mean temperature at the surface of the earth, under 760 m.m. 
pressure ; the velocity of sound 345 metres in a second. 
The atmosphere, however, contains water-stuff in every 
form, which wind raising accelerates and retards sound. 
The water-stuff always in the air, 0. s. p., is 347 centims. 
over the earth, the 1-7-29*78 of the mass of the atmosphere. 
This water propagating sound with a velocity to that in air 
as the respective specific heats 4*25 : 1, the mean increase 
of the velocity of sound through the whole of the atmo- 
sphere is 51 metres: — 
345 m. + 51 m. = 396 metres, 
which is the mean rotary velocity of the surface of the 
earth, 0. s. p. 
* Referring frequently to “ On some Properties of the Earth ’ (Wertheimer 
and Lea : London, 1880) I designate it by o. s. p. 
f In 1849 I wrote, not unprophetically, “ Without matter no sound. Sound 
deranges the parallelism of the light orbits of atoms. Sound gives an image. 
Sound displaces light; one might possibly observe oscillations of the dark 
rays of light by a strong sound ; the more elastic the medium through which 
the light moves, and the denser the medium on which it is received, the better. 
With patience one might magnetise iron by sound.” 
VOL. V. (THIRD SERIES.) 2 L 
