one quarter of the earth's density, or only one third greater than the
density of water. Consequently the visitor, in attempting to set foot
upon Jupiter, might find no solid supporting surface, but would be in a
situation as embarrassing as that of Milton's Satan when he undertook to
cross the domain of Chaos:

"Fluttering his pinions vain, plumb down he drops,
Ten thousand fathom deep, and to this hour
Down had been falling had not, by ill chance,
The strong rebuff of some tumultuous cloud.
Instinct with fire and niter, hurried him
As many miles aloft; that fury stayed,
Quenched in a boggy Syrtis, neither sea
Nor good dry land, nigh foundered, as he fares,
Treading the crude consistence, half on foot,
Half flying."

The probability that nothing resembling a solid crust, nor, perhaps,
even a liquid shell, would be found at the visible surface of Jupiter,
is increased by considering that the surface density must be much less
than the mean density of the planet taken as a whole, and since the
latter but little exceeds the density of water, it is likely that at the
surface everything is in a state resembling that of cloud or smoke. Our
imaginary visitor upon reaching Jupiter would, under the influence of
the planet's strong force of gravity, drop out of sight, with the speed
of a shot, swallowed up in the vast atmosphere of probably hot, and
perhaps partially incandescent, gases. When he had sunk--supposing his
identity could be preserved--to a depth of thousands of miles he might
not yet have found any solid part of the planet; and, perchance, there
is no solid nucleus even at the very center.