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 water about a
ship's propellers. Whether, when apergy is developed,
gravitation is temporarily annulled, or reversed like the late
attraction of a magnet when the current is changed, or whether it
is merely overpowered, in which case your motion will be the
resultant of the two, is an unsettled and not very important
point; for, though we know but little more of the nature of
electricity than was known a hundred years ago, this does not
prevent our producing and using it."

"Jupiter, when in opposition," he continued, "is about
380,000,000 miles from us, and it takes light, which travels at
the rate of 190,000 miles a second, just thirty-four minutes to
reach the earth from Jupiter. If we suppose the average speed of
your ship to be one- five-hundredth as great, it will take you
just eleven days, nineteen hours and twenty minutes to make the