the screw to the minute do you expect to get out of your windmill?"

"That depends on the power of the wind, sir. Do you think it is a
mad scheme?"

"It would impress the natives," said Compton, "and at any rate we
could start wheat-milling, you know, in case we came to the end of
our resources."

"There's no wheat in Central Africa, you duffer! Besides, sir, it's
mainly a question of gear. With a lever, cog-wheels, and a running
chain after the pattern of the cycle chain, one could----"

"And ball bearings," suggested Compton, slyly.

"Yes; and ball bearings--the friction would be reduced, and we could
get more power out of a screw and propeller than we could from four
paddles."

"You may be right," said Mr. Hume, thoughtfully.

"We don't want to take a large party, and I confess the water
transport has bothered me very much. The wind-mill, I am afraid, we
must leave to some other time, but the other part of your scheme is
worth placing before practical men, and I will give you a letter to
a friend of mine who had a boat built on the Thames."

Venning saw the friend the very next day; the friend gave him an
introduction to a member of a great firm of torpedo-boat builders on
the Thames, and this gentleman very kindly gave the matter five