of his own with which his flier was equipped--a clever improvement
of the ordinary Martian air compass, which, when set for a certain
destination, will remain constantly fixed thereon, making it only
necessary to keep a vessel's prow always in the direction of the
compass needle to reach any given point upon Barsoom by the shortest
route.

Carthoris' improvement upon this consisted of an auxiliary device
which steered the craft mechanically in the direction of the
compass, and upon arrival directly over the point for which the
compass was set, brought the craft to a standstill and lowered it,
also automatically, to the ground.

"You readily discern the advantages of this invention," he was saying
to Thuvan Dihn, who had accompanied him to the landing-stage upon
the palace roof to inspect the compass and bid his young friend
farewell.

A dozen officers of the court with several body servants were
grouped behind the jeddak and his guest, eager listeners to the
conversation--so eager on the part of one of the servants that he
was twice rebuked by a noble for his forwardness in pushing himself
ahead of his betters to view the intricate mechanism of the wonderful
"controlling destination compass," as the thing was called.

"For example," continued Carthoris, "I have an all-night trip before
me, as to-night. I set the pointer here upon the right-hand dial
which represents the eastern hemisphere of Barsoom, so that the
point rests upon the exact latitude and longitude of Helium. Then
I start the engine, roll up in my sleeping silks and furs, and with