to the Presence of a Medium pervading all Space., 513, 
in its capability of affecting the pressure of the solar matter: it 
is almost equalled by Venus, but it. is far superior to the other 
members of our system. If, however, the planets moved in circles, 
the peculiar action alluded to could only increase the tendency, 
of the spots to appear on certain sides of the sun, without mate- 
rially increasing the numbers visible during the year. When we 
take into consideration the changes occasioned by the eccentri- 
city of their orbits, the greatest effect must be ascribed to 
Mercury; Jupiter holds the next place; after which we must 
rank Saturn and the earth. But even admitting the compressi- 
bility of the sun’s materials, his mean diameter could not be 
altered more than the ;oth of an inch by the attraction of any of 
his planetary attendants; and the variation of temperature from 
this peculiar action cannot exceed giath part of a degree (F.). 
That so small a variation could be manifested in the appears 
ance of the sun’s disk, seems wholly improbable, especially if we 
adopt the estimate of Mr. Waterston, which assigns to the great 
orb a mean temperature of one thousand million degrees. 
Any effect which the planets may be supposed to occasion by 
their electric or magnetic forces must be also rendered extremely 
feeble in consequence of their great distance. If the great ocean 
of solar light is sensitive to the electricity or magnetism of Ju- 
piter, the nearest satellite of this planet must feel the power of 
his mysterious influence to an extent several million times as 
great ; yet no indications of such a fact have been observed. 
But supposing the sun’s motion through space to be concerned 
in maintaining his effulgence, the planets would derive a far 
more considerable influence from the general movement around 
the centre of gravity of our system. The position of Jupiter 
would change the progressive motion of the great luminary about 
twenty-four miles an hour; and the other planets will be at- 
tended with results proportional to their masses multiplied by 
the square roots of their distances. Now the amount of ether 
which the sun collects from space, and the density it attains on 
his surface, will depend on the rapidity of his translatory motion; 
but I have shown in the Philosophical Magazine for May 1858 
another way in which the position of the planets would increase 
or diminish the supply of ethereal fuel which sustains the great 
solar conflagration. 
The idea that the space-pervading medium is condensed by 
the attraction of the celestial orbs, is not to be considered a new 
hypothesis, but rather a necessary inference from that of Pro- 
fessor Encke. Were the density of the subtle fluid uniform, 
small and large planets would be so unequally affected by its re- 
sistance, that their orbits could not retain the relation necessary 
for their stability, and they must be destroyed by collisions long 
Phil, Mag. 8. 4, No. 143, Suppl, Vol. 21, 2 1L 
