gravity problem will not
put earthly visitors at a disadvantage, as it would on the very large
planets, but rather at a distinct advantage over the Martians."

"What do you expect to find on Mars?" I queried.

"That is a very comprehensive question, and any answer is the merest
guess-work, guided by a few known facts," replied the doctor. "The
principal controlling fact is the reduced gravitational attraction of
Mars, which will make things weigh about one-third as much as on the
Earth. The air will be far less dense than here. In the mineral kingdom
the dense metals will be very rare. I doubt if platinum will be found at
all; gold and silver very little; iron, lead, and copper will be
comparatively scarce, while aluminium may be the common and useful
metal. Gases should abound, and doubtless many entirely new to us will
be there. It is not unlikely that many of these will serve as foods for
the animals and intelligent beings. It is also quite possible that the
heavier gases may run in channels, like rivers, and be alive with winged
fish and chameleons."

"How about vegetation?" I suggested.

"The vegetable kingdom will certainly not be rank and luxurious, because
there is not enough sunlight or heat for that; nor will it be gnarled
and tough, but more likely spongy and cactus-like. The weak gravity will
oppose but a mild resistance to the activity and climbing propensities
of vegetable sap, however, which is likely to result in very tall,
slender trees. The forces that lie hidden in an acorn should be able to
build a most grandly towering oak on Mars. Among the animals the species
of upright, two-legged things is apt to abound. There is no reason for
four legs when the body weighs but little. On the Earth an extremely
strong development of the lower limbs is necessary for upright things,
as is shown in the cases of kangaroos and men. In order that a cow might
go comfortably on two legs, she would have to be furnished with the
hind-legs of an elephant; but not so on Mars. Creeping things would be
very few, and it is possible that fish may fly in the water with a short
pair of wings. What four-legged animals there are will very likely be
large and monstrous; for an enormous animal could exist comfortably and
move about easily without clumsiness. For instance, an earthly elephant
transferred to Mars would weigh only one-third as much, and so there
might well be elephants three times as large as ours, perfectly able to