start?"

"That's what we were," replied Jack. "Oh, Mark, but I'm glad to see you
again! I didn't know what to think. You acted so strange--or, rather,
the fellow we thought was you had me guessing!"

"Good land a' massy!" exclaimed Washington White, as he stood in the
doorway, with Andy Sudds behind him. "Am dere two Marks? What's up,
anyhow?"

"Don't let that fellow get away--the fellow who passed himself off as
me!" shouted Mark. "Lock him up! There's some mystery about him that
must be explained. He's a dangerous man to be at large."

Professor Henderson turned back to enter the projectile. Jack advised
Andy to get his gun ready, with which to threaten the scoundrel in case
of necessity.

At that instant there sounded a crash of glass, and the whole front of
the big observation window in the side of the _Annihilator_ was smashed
to atoms. A figure leaped--a figure which no longer had its head
bandaged, and whose arm was no longer in a sling--the figure of a man--
the mysterious man who had held Mark a prisoner!

"There he goes!" shouted Jack. "Catch him, somebody! Andy, where's your
gun?"

"I'll have it in a jiffy!" cried the hunter, as he dashed back to get
it.