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POPULAR SCIENCE REVIEW. 
tion that the globe is not formed of substances unlike any with 
which we are familiar. Even this assumption, though it is one 
which few would care to maintain in the present position of 
our knowledge, amounts after all to an admission of the chief 
point which I am endeavouring to maintain : it is one way — 
hut a very fanciful way — of inferring that Jupiter is utterly 
dissimilar to the earth. Eejecting it, as we safely may, we 
find the small density of Jupiter not merely unexplained, but 
manifestly inexplicable. 
All our reasoning has been based on the assumption that the 
atmosphere of Jupiter exists at a temperature not greatly dif- 
fering from that of our own atmosphere. If we assume instead 
an exceedingly high temperature, abandoning of course the 
supposition that Jupiter is an inhabited world, we no longer 
find any circumstances which are self-contradictory or in- 
credible. 
To begin with, we may on such an assumption find at once 
a parallel to Jupiter’s case in that of the Sun. For the Sun is 
an orb attracting his atmospheric envelope and the material 
of his own solid or liquid surface (if he has any) far more 
mightily that Jupiter has been known to do. All the difficul- 
ties considered in the case of Jupiter would be enormously 
enhanced in the case of the Sun, if we forgot the fact that the 
Sun’s globe is at an intense heat from surface to centre. Now 
we know that the Sun is intensely hot because we feel the 
heat that he emits, and recognise the intense lustre of his 
photosphere ; so that we are not in danger of overlooking this 
important circumstance in his condition. Jupiter gives out no 
heat that we can feel, and assuredly Jupiter does not emit an 
intense light of his own. But, when we find that difficulties 
precisely corresponding in kind, though not in degree, to those 
which we should encounter if we discussed the Sun’s condition 
in forgetfulness of his intense heat, exist also in the case of 
Jupiter, it appears manifest that we may safely adopt the conclu- 
sion that Jupiter is intensely heated, though not nearly to the 
same degree as the Sun. 
We have thus been led by a perfectly distinct and indepen- 
dent line of reasoning to the very conclusion which I have 
advocated elsewhere on other grounds, viz. that Jupiter is in 
fact a miniature sun as respects heat, though emitting but a 
relatively small proportion of light. I would invite special 
attention to the circumstance that the evidence on which this 
conclusion had been based was already cumulative. And now 
a fresh line of evidence, in itself demonstrative I conceive, has 
been adduced. Moreover I have not availed myself of the 
argument, very weighty in my opinion, on which Mr. Mattieu 
Williams has based similar conclusions respecting the tempera- 
