Across the Zodiac (7 page)

I mean that, apart from the polar compression, the shape seemed as if
the spheroid were irregularly squeezed; so that though not broken by
projection or indentation, the limb did not present the regular
quasi-circular curvature exhibited in the focus of our telescopes.
Also, between the inner ring and the planet, with a power of 500, I
discerned what appeared to be a dark purplish ring, semi-transparent,
so that through it the bright surface of Saturn might be discerned as
through a veil. Mercury shone brightly several degrees outside the
halo surrounding the Earth's black disc; and Venus was also visible;
but in neither case did my observations allow me to ascertain anything
that has not been already noted by astronomers. The dim form of Uranus
was better defined than I had previously seen it, but no marking of
any kind was perceptible.

Rising from my second, or, so to speak, midday rest, and having busied
myself for some little time with what I may call my household and
garden duties, I observed the discometer at 1h. (or 5 P.M.). It
indicated about two hundred terrestrial radii of elevation. I had, of
course, from the first been falling slightly behind the Earth in her
orbital motion, and was no longer exactly in opposition; that is to
say, a line drawn from the Astronaut to the Earth's centre was no
longer a prolongation of that joining the centres of the Earth and
Sun. The effect of this divergence was now perceptible. The earthly
corona was unequal in width, and to the westward was very distinctly
brightened, while on the other side it was narrow and comparatively
faint. While watching this phenomenon through the lower lens, I
thought that I could perceive behind or through the widest portion of
the halo a white light, which at first I mistook for one of those
scintillations that had of late become scarcely discernible. But after
a time it extended visibly beyond the boundary of the halo itself, and
I perceived that the edge of the Sun's disc had come at last into
view. It was but a minute and narrow crescent, but was well worth
watching. The brightening and broadening of the halo at this point I
perceived to be due, not to the Sun's effect upon the atmosphere that
produced it, but chiefly to the twilight now brightening on that limb
of the Earth's disc; or rather to the fact that a small portion of
that part of the Earth's surface, where, if the Sun were not visible,
he was but a very little below the horizon, had been turned towards
me. I saw through the telescope first a tiny solar crescent of intense
brightness, then the halo proper, now exceedingly narrow, and then
what looked like a silver terrestrial crescent, but a mere thread,
finer and shorter than any that the Moon ever displays even to
telescopic observers on Earth; since, when such a minute portion of
her illuminated surface is turned towards the Earth, it is utterly
extinguished to our eyes by the immediate vicinity of the Sun, as was
soon the case with the terrestrial crescent in question. I watched
long and with intense interest the gradual change, but I was called
away from it by a consideration of no little practical moment. I must
now be moving at a rate of nearly, if not quite, 40,000 miles an hour,
or about a million miles per diem. It was not my intention, for
reasons I shall presently explain, ever greatly to exceed this rate;
and if I meant to limit myself to a fixed rate of speed, it was time
to diminish the force of the apergic current, as otherwise before its
reduction could take effect I should have attained an impulse greater
than I desired, and which could not be conveniently or easily
diminished when once reached. Quitting, therefore, though reluctantly,
my observation of the phenomena below me, I turned to the apergion,
and was occupied for some two or three hours in gradually reducing the
force as measured by the cratometer attached to the downward
conductor, and measuring with extreme care the very minute effect
produced upon the barycrite and the discometer. Even the difference
between 200 and 201 radii of elevation or apogaic distance was not
easily perceptible on either. It took, of course, much more minute
observation and a much longer time to test the effect produced by the
regulation of the movement, since whether I traveller forty,
forty-five, or forty-two thousand miles in the course of one hour made
scarcely any difference in the diameter of the Earth's disc, still
less, for reasons above given, in the gravity. By midnight, however, I
was satisfied that I had not attained quite 1,000,000 miles, or 275
terrestrial radii; also that my speed was not greater than 45,000
miles (11-1\4 radii) per hour, and was not, I thought, increasing. Of
this last point, however, I could better satisfy myself at the end of
my four hours' rest, to which I now betook myself.

I woke about 4h. 30m., and on a scrutiny of the instruments, felt
satisfied that I was not far out in my calculations. A later hour,
however, would afford a more absolute certainty. I was about to turn
again to the interesting work of observation through the lens in the
floor, when my attention was diverted by the sight of something like a
whitish cloud visible through the upper window on my left hand.
Examined by the telescope, its widest diameter might be at most ten
degrees. It was faintly luminous, presenting an appearance very
closely resembling that of a star cluster or nebula just beyond the
power of resolution. As in many nebulae, there was a visible
concentration in one part; but this did not occupy the centre, but a
position more resembling that of the nucleus of a small tailless
comet. The cloudlet might be a distant comet, it might be a less
distant body of meteors clustering densely in some particular part of
their orbit; and, unfortunately, I was not likely to solve the
problem. Gradually the nebula changed its position, but not its form,
seeming to move downwards and towards the stern of my vessel, as if I
were passing it without approaching nearer. By the time that I was
satisfied of this, hunger and even faintness warned me that I must not
delay preparing my breakfast. When I had finished this meal and
fulfilled some necessary tasks, practical and arithmetical, the hand
of the chronometer indicated the eighth hour of my third day. I turned
again somewhat eagerly to the discometer, which showed an apparent
distance of 360 terrestrial radii, and consequently a movement which
had not materially varied from the rate of 11-1/4 radii per hour. By
this time the diameter of the Earth was not larger in appearance than
about 19', less than two-thirds that of the Sun; and she consequently
appeared as a black disc covering somewhat more than one-third of his
entire surface, but by no means concentrical. The halo had of course
completely disappeared; but with the vernier it was possible to
discern a narrow band or line of hazy grey around the black limb of
the planet. She was moving, as seen from the Astronaut, very slightly
to the north, and more decidedly, though very slowly, to the eastward;
the one motion due to my deliberately chosen direction in space, the
other to the fact that as my orbit enlarged I was falling, though as
yet slowly, behind her. The sun now shone through, the various
windows, and, reflected from the walls, maintained a continuous
daylight within the Astronaut, as well diffused as by the atmosphere
of Earth, strangely contrasting the star-spangled darkness outside.

At the beginning as at the end of my voyage, I steered a distinct
course, governed by considerations quite different from those which
controlled the main direction of my voyage. Thus far I had simply
risen straight from the Earth in a direction somewhat to the
southward, but on the whole "in opposition," or right away from the
Sun. So, at the conclusion of my journey, I should have to devote some
days to a gradual descent upon Mars, exactly reversing the process of
my ascent from the Earth. But between these two periods I had
comparatively little to do with either planet, my course being
governed by the Sun, and its direction and rate being uniform. I
wished to reach Mars at the moment of opposition, and during the whole
of the journey to keep the Earth between myself and the Sun, for a
reason which may not at first be obvious. The moment of opposition is
not necessarily that at which Mars is nearest to the Earth, but is
sufficiently so for practical calculation. At that moment, according
to the received measurement of planetary distances, the two would be
more than 40 millions of miles apart. In the meantime the Earth,
travelling on an interior or smaller orbit, and also at a greater
absolute speed, was gaining on Mars. The Astronaut, moving at the
Earth's rate under an impulse derived from the Earth's revolution
round the Sun (that due to her rotation on her own axis having been
got rid of, as aforesaid), traveller in an orbit constantly widening,
so that, while gaining on Mars, I gained on him less than did the
Earth, and was falling behind her. Had I used the apergy only to drive
me directly outward from the Sun, I should move under the impulse
derived from the Earth about 1,600,000 miles a day, or 72 millions of
miles in forty-five days, in the direction common to the two planets.
The effect of the constantly widening orbit would be much as if the
whole motion took place on one midway between those of the Earth and
Mars, say 120 millions of miles from the Sun. The arc described on
this orbit would be equivalent to 86 millions of miles on that of
Mars. The entire arc of his orbit between the point opposite to that
occupied by the Earth when I started and the point of opposition—the
entire distance I had to gain as measured along his path—was about
116 millions of miles; so that, trusting to the terrestrial impulse
alone, I should be some 30 millions behindhand at the critical moment.
The apergic force must make up for this loss of ground, while driving
me in a direction, so to speak, at right angles with that of the
orbit, or along its radius, straight outward from the Sun, forty odd
millions of miles in the same time. If I succeeded in this, I should
reach the orbit of Mars at the point and at the moment of opposition,
and should attain Mars himself. But in this I might fail, and I should
then find myself under the sole influence of the Sun's attraction;
able indeed to resist it, able gradually to steer in any direction
away from it, but hardly able to overtake a planet that should lie far
out of my line of advance or retreat, while moving at full speed away
from me. In order to secure a chance of retreat, it was desirable as
long as possible to keep the Earth between the Astronaut and the Sun;
while steering for that point in space where Mars would lie at the
moment when, as seen from the centre of the Earth, he would be most
nearly opposite the Sun,—would cross the meridian at midnight. It was
by these considerations that the course I henceforward steered was
determined. By a very simple calculation, based on the familiar
principle of the parallelogram of forces, I gave to the apergic
current a force and direction equivalent to a daily motion of about
750,000 miles in the orbital, and rather more than a million in the
radial line. I need hardly observe that it would not be to the apergic
current alone, but to a combination of that current with the orbital
impulse received at first from the Earth, that my progress and course
would be due. The latter was the stronger influence; the former only
was under my control, but it would suffice to determine, as I might
from time to time desire, the resultant of the combination. The only
obvious risk of failure lay in the chance that, my calculations
failing or being upset, I might reach the desired point too soon or
too late. In either case, I should be dangerously far from Mars,
beyond his orbit or within it, at the time when I should come into a
line with him and the Sun; or, again, putting the same mischance in
another form, behind him or before him when I attained his orbit. But
I trusted to daily observation of his position, and verification of my
"dead reckoning" thereby, to find out any such danger in time to avert
it.

The displacement of the Earth on the Sun's face proved it to be
necessary that the apergic current should be directed against the
latter in order to govern my course as I desired, and to recover the
ground I had lost in respect to the orbital motion. I hoped for a
moment that this change in the action of the force would settle a
problem we had never been able to determine. Our experiments proved
that apergy acts in a straight line when once collected in and
directed along a conductor, and does not radiate, like other forces,
from a centre in all directions. It is of course this radiation—
diffusing the effect of light, heat, or gravity over the surface of a
sphere, which surface is proportionate to the square of the
radius—that causes these forces to operate with an energy inversely
proportionate, not to the distance, but to its square. We had no
reason to think that apergy, exempt as it is from this law, would be
at all diminished by distance; and this view the rate of acceleration
as I rose from the Earth had confirmed, and my entire experience has
satisfied me that it is correct. None of our experiments, however, had
indicated, or could well indicate, at what rate this force can travel
through space; nor had I yet obtained any light upon this point. From
the very first the current had been continuous, the only interruption
taking place when I was not five hundred miles from the Earth's
surface. Over so small a distance as that, the force would move so
instantaneously that no trace of the interruption would be perceptible
in the motion of the Astronaut. Even now the total interruption of the
action of apergy for a considerable time would not affect the rate at
which I was already moving. It was possible, however, that if the
current had been hitherto wholly intercepted by the Earth, it might
take so long a time in reaching the Sun that the interval between the
movement of the helm and the response of the Astronaut's course
thereto might afford some indication of the time occupied by the
current in traversing the 96-1/2 millions of miles which parted me
from the Sun. My hope, however, was wholly disappointed. I could
neither be sure that the action was instantaneous, nor that it was
otherwise.