the
lightest of all known metals, having a specific gravity of only two,
which last property will be of great use to you, for of course the more
weight you have to propel the more apergetic repulsion you will have to
develop."

"I will get some drawing-paper I left outside in my trap," said
Ayrault, "when with your ideas we may arrive at something definite,"
saying which, he left the room.

"He seems very cynical in his ideas of life and the world in general,"
said Secretary Stillman, "for a man of his age, and one that is
engaged."

"You see," replied Bearwarden, "his fiancee is not yet a senior, being
in the class of two thousand and one at Vassar, and so cannot marry him
for a year. Not till next June can this sweet girl graduate come forth
with her mortar-board and sheepskin to enlighten the world and make him
happy. That is, I suspect, one reason why he proposed this trip."

CHAPTER VII.

HARD AT WORK.

In a few moments Ayrault returned with pencils, a pair of compasses,
and paper.

"Let us see, in the first place," said Deepwaters, "how long the
journey will take. Since a stone falls 16.09 feet the first second,
and 64+ feet the next, it is easy to calculate at what rate your speed
would increase with the repulsion twice that of the ordinary traction.
But I think this would be too slow. It will be best to treble or
quadruple the apergetic charge, which can easily be done, in which case
your speed will exceed the muzzle-velocity of a projectile from a
long-range gun, in a few seconds. As the earth's repulsion decreases,
the attraction of mars and Jupiter will increase, and, there being no
resistance, your gait will become more and more rapid till it is
necessary to reverse the charge to avoid being dashed to pieces or
being consumed like a falling star by the friction in passing through
Jupiter's atmosphere. You can be on the safe side by checking your
speed in advance. You must, of course, be careful to avoid collisions
with meteors and asteroids but if you do, they will be of use to you,
for by attracting or repelling them you can change your course to suit
yourself, and also theirs in inverse ratio to their masses. Jupiter's
moons will be like head and stern lines in enabling you to choose the
part of the surface on which you wish to land. With apergy it is as
essential to have some heavy body on which to work, within range, as to
have wa