to the Presence of a Medium pervading all Space. 511 
The theory which ascribes the sun’s light to the incessant 
fall of meteors to his surface, and which I have controverted in 
my article in the Philosophical Magazine for December 1858, 
appears to have been suggested by the recently discovered rela- 
tion between heat and mechanical energy. From this it may be 
estimated that a pound of solid matter, falling to the sun from 
a distance of 35,000,000 miles, is capable of generating at 
his surface an amount of heat about 4000 times as great as 
could be developed by the combustion of a pound of coal in 
oxygen gas. But the large amount of heat arising from the 
combustion of hydrogen, and other facts and principles con- 
nected with thermal agencies, give support to the opinion that 
the development of heat must be proportional to the intensity 
of the chemical forces by which it is produced; and these must 
be commensurate with the degree of elasticity between the 
elements concerned in the calorific or the illuminating action. We 
have therefore no grounds for supposing that the accession of 
temperature imparted to the solar orb by the fall of a body, 
even from an infinite distance, is necessarily greater than that 
originating from the chemical action of an equal amount of 
matter, the elements of which were so elastic as to diffuse them- 
selves into space, in opposition to the attractive power of suns 
and planets. If the undulatory theory of light be admitted, 
the medium which conveys it with nearly a million times the 
rapidity of sound, must have a modulus of elasticity almost 
1,000,000,000,000 times as great as that of common air. But 
though not regarding the ether which gives birth to solar light as 
sO Inconceivably elastic, we may safely presume that no matter is 
better adapted for sustaining the great fountain of brilliancy by 
energetic chemical action, than that whose particles are asso- 
ciated with forces sufficiently powerful to cause its diffusion 
through universal space. 
That the fall of meteors is far more frequent and more con- 
spicuous on the sun than on the earth cannot be questioned. If 
these small bodies are to be regarded as independent occupants 
of space, two large spheres, moving with the same velocity through 
the region in which they are located, would each be likely to 
receive a number of them proportional to its mass multiplied by 
its diameter. The circumstances in which the earth and sun 
are placed will change, to some extent, their relative capabilities 
of receiving these foreign bodies; but the facts which Mr. Car- 
rington’s observations have made known in regard to meteoric 
phenomena on the solar disk are not inconsistent with what 
might be reasonably expected, and do not indicate any special 
provision for feeding our central luminary with regular supplies 
of meteorites. 
