t equal to the
attraction of the other; and if a body is stopped in that fatal spot it
will be anchored there for ever, by the equally matched forces tugging
in opposite directions. There is such a dead line between all the
planets, and our principal danger lies in falling into one of these, for
we should remain there a twinkling star throughout eternity! We must
trust to our momentum to carry us past this point, and into space where
the gravitational attraction of the other planet is paramount. Then we
must promptly change our current from negative to positive, so that the
other planet will attract us to her. Otherwise, she would repel us back
to the dead line.

"With a positive current we are now literally falling into the new
planet. We need not land unless we wish, for as soon as we enter a
resisting atmosphere we can steer a course lacking barely a quarter of
being directly away from the planet, just as you can sail a boat three
quarters against the wind."

"But suppose you experiment at making a landing on this new planet?" I
suggested.

"Very well. Of course, as soon as we enter an atmosphere, it behoves us
to travel slowly to avoid overheating. We can still safely travel
several hundred miles an hour, however. We continue falling until rather
near the planet; then, turning the rudder gently down, we can sail
around and around the planet until we choose our landing place. Gently
reversing currents, a mild negative one soon overcomes our momentum.
Tempering our currents experimentally to the pressure of the air, we
can, if we desire, float like a feather and be wafted with every breeze.
Just a suspicion of a positive current brings us gently to the surface,
and, when we have cooled, we unscrew the rear port-hole and crawl out to
explore a new world."

I had mentally made the trip, and was not only intensely interested, but
infinitely pleased. I was lost for some time with my imagination on the
new sphere, but presently my mind returned to the practical side of the
question, and I inquired,--

"Are you quite sure that ten thousand dollars will be sufficient to
build and fully equip the projectile?"

"Yes, quite certain," he answered with decision. "It will be ample for
that and for the expenses of forming a corporation to own my patents and
exploit the invention. It is easy to see the projectile will be cheap of
construction. No machinery is necessary; no strong building to withstand
enormous shocks or anyt