ouds of every kind. The only objection to his work
is that he is a bit too thorough at times, and treats people out here as
if they were meant to cook. Now then, look back as well as forward; the
camels march like a line of grenadiers. Just as if they had been
drilled."

"But so slowly--so slowly," said Frank, with a sigh.

"Here, look sharp, Sol!" cried the professor. "Get higher; there's
another cloud."

"How can you be so light-hearted at a time like this?" said Frank
bitterly.

"Because `A merry heart goes all the day; your sad tires in a mile-a,'
as Shakespeare says. Because we should never carry out our plans to
success if we went at them with sad hearts. I found that out over many
of my searches here. An eager, cheery captain makes an eager, cheery
crew who laugh at wreck. Now then, I am going to demolish--with the
help of the sun--that great, dense black cloud that has just risen above
your mental horizon, my sable friend. Your fresh cloud is the slow one.
Now, you must remember that we have given up civilisation, steam,
electricity, and the like, to take up the regular and only way of
travelling here in the desert. Some day, perhaps, we shall have the
railway and wires from north to south; but until we do we must travel by
caravan, and to travel by caravan you must travel in caravan fashion, in
the old, long proved style. You would like to hurry on and do fifty
miles the first day, instead of ten or fifteen."

"Of course," said Frank, "with such things at stake."

"Exactly, my dear boy, and very naturally. Well, we'll say you'd like
to go forty miles to-day?"

"Yes."

"Couldn't be done. Men can't walk forty miles over hot sand under a
desert sun."

"Then why not have had more camels?"

"Because camels can suffer like men. You would knock up your desert
ships, and make them sore-footed the first day, have great difficulty in
getting them half the distance the next day, half that the third, and no
distance at all the fourth."

"So bad as that?" said Frank.

"Most likely a good deal worse. Now we have old Ibrahim and his men,
who know camels exactly, understand their constitutions, how much they
can do, and how to get them to do it. You see, we are not going on a
week's journey."

"A week's!" said Frank bitterly; "at this rate it will be six months."

"Perhaps a year's," said the professor quietly.

"A year's?"

"Possibly; and if a camel should break down we can't send round t