第 12 页

that it was less than thirty million miles from them now, or five

millions nearer than it had ever been to them before. This

reduction in distance, and the clearness of the void through

which they saw it, made it a splendid sight, its disk showing

clearly. From hour to hour its size and brightness increased,

till towards evening it looked like a small, full moon, the sun

shining squarely upon it. They calculated that on the course

they were moving they should pass about nine hundred thousand

miles to the right or behind it, since it was moving towards

their left. They were interested to see what effect the mass of

Mars would have on the Callisto, and saw here a chance of still

further increasing their speed. Notwithstanding its tremendous

rate, they expected to see the Callisto swerve from its straight

line and move towards Mars, whose orbital speed of nine hundred

miles a minute they thought would take it out of the Callisto's

way, so that no actual collision would occur even if their

air-ship were left to her own devices.

Towards evening they noticed through their glasses that several

apparently island peaks in the southern hemisphere, which was

turned towards them, became white, from which they concluded that

a snow-storm was in progress. The south polar region was also

markedly glaciated, though the icecap was not as extensive as

either of those at the poles of the earth.

"As the Martian winters must be fully as severe as ours," said

Cortlandt, "on account of their length, the planet's distance

from the sun, and the twenty-seven and a half degrees inclination

of its axis, we can account for the smallness of its ice-caps

only by the fact that its oceans cover but one fourth of its

surface instead of three quarters, as on the earth, and there is

consequently a smaller evaporation and rain and snow-fall."

They were too much interested to think of sleeping that night,

and so, after dining comfortably returned to their observatory.

When within four million miles of Mars the Callisto began to

swerve perceptibly, its curve, as when near the moon beginning

with a spiral. They swung on unconcernedly, however, knowing

they could check their approach at any time. Soon Mars appeared

to have a diameter ten times as great as that of the moon, and

promised shortly to occupy almost one side of their sky.

"We must be on the lookout for the satellites," said Cortlandt;

"a collision with either would be worse than a wreck on a desert

island."

They therefore turned their glasses in the direction of the

satellites.

"Until Prof. Hall, at Washington, discovered the two satellites

in 1877," he continued, "Mars was supposed to be without moons.

The outer one, Deimos, is but six miles in diameter, and revolves

about its primary in thirty hours and eighteen minutes, at a

distance of fourteen thousand six hundred miles. As it takes but

little longer to complete a revolution than Mars does to rotate

on its axis, it remains in the Martial sky one hundred and

thirty-two hours between rising and setting, passing through all

the phases from new moon to full and back again four times; that

is, it swings four times around Mars before going below the

horizon. It is one of the smallest bodies discovered with a

telescope. The inner one, Phobos, is considerably larger, having

a diameter of about twenty miles. It is but twenty-seven hundred

miles from Mars's surface, and completes its revolution in seven

hours and thirty-eight minutes, which is shorter than any other

known period, Jupiter's nearest moon being the next, with eleven

hours and fifty- nine minutes. It thus revolves in less than a

third of the time Mars takes to rotate, and must consequently

rise in the west and set in the east, as it is continually

running ahead of the surface of the planet, though the sun and

all the other stars rise and set on Mars in the same way as on

the earth."

When about fifteen thousand miles from Mars, they sighted Deimos

directly ahead, and saw that they should pass on its left--i. e.,

behind--for it was moving across them. The sun poured directly

upon it, making it appear full and showing all its features.

There were small unevennesses on the surface, apparently seventy

or a hundred feet high, which were the nearest approach to

mountains, and they ran in ridges or chains. There were also

unmistakable signs of volcanic action, the craters being large

compared with the size of the planet, but shallow. They saw no

signs of water, and the blackness of the shadows convinced them

there was no air. They secured two instantaneous photographs of

the little satellite as the Callisto swept by, and resumed their

inspection of Mars. They noticed red and brownish patches on the

peaks that had that morning turned white, from which they

concluded that the show had begun to melt under the warm spring

sun. This strengthened the belief they had already formed, that

on account of its twenty-seven and a half degrees inclination the

changes in temperature on Mars must be great and sudden. So

interested were they with this, that they did not at first see a

large and bright body moving rapidly on a course that converged

with theirs.

"We must be ready to repel boarders," said Bearwarden, observing

it for the first time and fixing his glass upon it. "That must

be Phobos."

Not ten miles off they beheld Mars's inner moon, and though their

own speed caused them to overtake and rush by it like a

whirlwind, the satellite's rapid motion in its orbit, in a course

temporarily almost parallel with theirs, served to give them a

chance the better to examine it. Here the mountain ranges were

considerably more conspicuous than on Deimos, and there were

boulders and loose stones upon their slopes, which looked as if

there might at some time have been frost and water on its

surface; but it was all dry now, neither was there any air. The

evidences of volcanic action were also plainly visible, while a

noticeable flattening at the poles showed that the little body

had once rotated rapidly on its axis, though whether it did so

still they had not time to ascertain. When abreast of it they

were less than two miles distant, and they secured several

instantaneous impressions, which they put aside to develop later.

As the radius of Phobos's circle was far shorter than that of the

parabolic curve they were making, it began to draw away, and was

rapidly left behind. Applying the full apergetic force to Mars

and the larger moon, they shot away like an arrow, having had

their speed increased by the planet's attraction while

approaching it, and subsequently by repulsion.

"Either of those," said Bearwarden, looking back at the little

satellites, "would be a nice yacht for a man to explore space on.

He would also, of course, need a sun to warm him, if he wished to

go beyond this system, but that would not have to be a large

affair--in fact, it might be smaller than the planet, and could

revolve about it like a moon."

"Though a sun of that size," replied Cortlandt, "might retain its

heat for the time you wished to use it, the planet part would be

nothing like as comfortable as what we have here, for it would be

very difficult to get enough air-pressure to breathe on so small

a body, since, with its slight gravitation-pull, to secure

fifteen pounds to the square inch, or anything like it, the

atmosphere would have to extend thousands of miles into space, so

that on a cloudy day you would be in darkness. It would be

better, therefore, to have such a sun as you describe and

accompany it in a yacht or private car like this, well stocked

with oxygen and provisions. When passing through meteoric swarms

or masses of solid matter, collision with which is the most

serious risk we run, the car could follow behind its sun instead

of revolving around it, and be kept from falling into it by

partially reversing the attraction. As the gravitation of so

small a sun would be slight, counteracting it for even a

considerable time would take but little from the batteries."

"There are known to be several unclaimed masses," added Ayrault,

"with diameters of a few hundred yards, revolving about the earth

inside the orbit of the moon. If in some way two of these could

be brought into sufficiently violent collision, they would become

luminous and answer very well; the increase in bulk as a result

of the consolidation, and the subsequent heat, about serving to

bring them to the required size. Whenever this sun showed spots

and indications of cooling, it could be made to collide with the

solid head of some comet, or small asteroid, till its temperature

was again right; while if, as a result of these accretions, it

became unwieldy, it could be caused to rotate with sufficient

rapidity on its axis to split, and we should have two suns

instead of one."

"Bravo!" said Bearwarden. "There is no limit to what can be

done. The idea of our present trip would have seemed more

chimerical to people a hundred years ago than this new scheme

appears now."

Thus they sat and talked, or studied maps and star- charts, or

the stars themselves, while the hours quickly passed and they

shot through space. They had now a straight stretch of over

three hundred million miles, and had to cross the orbits of

innumerable asteroids on the way. The apparent size of the sun

had by this time considerably decreased, and the interior of the

Callisto was no longer uncomfortably warm. They divided the day

into twenty-four hours from force of habit, and drew the shades

tightly during what they considered night, while Bearwarden

distinguished himself as a cook.

CHAPTER III.

HEAVENLY BODIES.

The following day, while in their observatory, they saw something

not many miles ahead. They watched it for hours, and in fact all

day, but notwithstanding their tremendous speed they came but

little nearer.

"They say a stern chase is a long one," said Bearwarden; but that

beats anything I have ever seen."

After a while, however, they found they WERE nearer, the time

taken having been in part due to the deceptive distance, which

was greater than they supposed.

"A comet!" exclaimed Cortlandt excitedly. "We shall really be

able to examine it near."

"It's going in our direction," said Ayrault, "and at almost

exactly our speed."

While the sun shone full upon it they brought their camera into

play, and again succeeded in photographing a heavenly body at

close range. The nucleus or head was of course turned towards

the sun; while the tail, which they could see faintly, preceded

it, as the comet was receding towards the cold and dark depths of

space. The head was only a few miles in diameter, for it was a

small comet, and was composed of grains and masses of stone and

meteoric iron. Many of the grains were no larger than peas or

mustard-seeds; no mass was more than four feet in diameter, and

all of them had very irregular shapes. The space between the

particles was never less than one hundred times their masses.

"We can move about within it," said Ayrault, as the Callisto

entered the aggregation of particles, and moved slowly forward

among them.

The windows in the dome, being made of toughened glass, set

somewhat slantingly so as to deflect anything touching them, and

having, moreover, the pressure of the inside air to sustain them,

were fairly safe, while the windows in the sides and base were

but little exposed. Whenever a large mass seemed dangerously

near the glass, they applied an apergetic shock to it and sent it

kiting among its fellows. At these times the Callisto recoiled

slightly also, the resulting motion in either being in inverse

ratio to its weight. There was constant and incessant movement

among the individual fragments, but it was not rotary. Nothing

seemed to be revolving about anything else; all were moving,

apparently swinging back and forth, but no collisions took place.

When the separate particles got more than a certain distance

apart they reapproached one another, but when seemingly within

about one hundred diameters of each other they swung off in some

other direction. The motion was like that of innumerable

harp-strings, which may approach but never strike one another.

After a time the Callisto seemed to become endowed with the same

property that the fragments possessed; for it and they repelled

one another, on a near approach, after which nothing came very

near.

Much of the material was like slag from a furnace, having

evidently been partly fused. Whether this heat was the result of

collision or of its near approach to the sun at perihelion, they

could not tell, though the latter explanation seemed most simple

and probable. When at about the centre of the nucleus they were

in semi-darkness--not twilight, for any ray that succeeded in

penetrating was dazzlingly brilliant, and the shadows, their own

included, were inky black. As they approached the farther side

and the sunlight decreased, they found that a diffused luminosity

pervaded everything. It was sufficiently bright to enable them

to see the dark side of the meteoric masses, and, on emerging

from the nucleus in total darkness, they found the shadow

stretching thousands of miles before them into space.

"I now understand," said Bearwarden, "why stars of the sixth and

seventh magnitude can be seen through thousands of miles of a

comet's tail. It is simply because there is nothing in it. The

reason ANY stars are obscured is because the light in the tail,

however faint, is brighter than they, and that light is all that

the caudal appendage consists of, though what produces it I

confess I am unable to explain. I also see why the tail always