This time I was
prepared for the shock of acceleration, but the action was maintained
for several seconds and I found the pressure against my back growing
painful. Then it was relieved, and I glanced at the altimeter. Its
needle had reached the end of the scale, which was graduated to eighty
thousand feet!

"Good Lord!" I exclaimed. "Do you mean to tell me that we are more than
sixteen miles in the air?"

"Nearly thirty," replied Hart, pointing to another dial which I had not
seen. This one was graduated in miles above sea-level, and its needle
wavered between the twenty-nine and thirty mark!

* * * * *

Again Hart pressed the rocket buttons, and we shot still higher into the
heavens. Thirty, forty, fifty miles registered the meter, and still we
climbed.

"Great Scott!" blurted a voice I knew was my own, though I had no
consciousness of willing the speech. "At this rate we'll reach the
moon!"

"We could, if we wished," was Hart's astounding reply; "I wish you
wouldn't say too much about it when we return. We have oxygen to breathe
and an air-tight vessel to retain it. With the fuel we are using, we
could easily do it, provided a sufficient supply were available.
However, the _Pioneer_ does not have large enough storage tanks as yet,
and, of course, we cannot now replenish our supply with sufficient
rapidity, for the atmosphere has become very rare indeed--where we are.
My ultimate object, though, in building the _Pioneer_, was to construct
a vessel that is capable of a trip to the moon."

"You think you could reach a great enough velocity to escape the
gravitational pull of the earth?" I asked, marveling more and more at
the temerity and resourcefulness of my science-minded friend.

"Absolutely," he replied. "The speed required is less than seven miles a
second, and I have calculated that the _Pioneer_ can do no less than
twenty."

Mentally I multiplied by sixty. I could hardly credit the result. Twelve
hundred miles a minute!

"But, how about the acceleration?" I ventured. "Could the human body
stand up under the strain?"

"That is the one problem remaining," he replied; "and I am now working
on a method of neutralizing it. From the latest results of our
experiments, George and I are certain of its feasibility."

* * * * *

The _Pioneer_ was now losing altitude once more, and Hart played the
beam of the searchlight in all directions as we d