and live on them."

"There is one thing I could never understand," remarked Tom, "and that
is, why the sap of the trees goes upwardly."

"I shall try and answer that question by asking another. If you put the
end of a piece of blotting paper in water, what causes the water to
travel along to the other end?"

"That is just as much a mystery," he replied.

"But as you know that to be so, because you can see the process, it will
enable me to explain the principle of the movement of the sap. A wick in
a lamp becomes saturated and the oil travels upwardly as long as the
upper end is burning; but as soon as the light is put out the oil ceases
to creep toward the burned end."

"But in the case of a tree there is nothing to do that same thing."

"That is what the sun does. It shines on the leaf, and absorbs the sap,
or portions of it, and the sap tries to move upwardly to again moisten
the dried pores of the wood."

"I always thought the sap moved upwardly, because the tree was alive."

"The blotting paper and the wick are not alive, are they? Still, you see
the same process going on. This is due to what is termed capillary
attraction. Suppose you take two tubes, one larger than the other, each
open at both ends, and stand them in water. The water will rise in the
tubes above the surface of the water outside, and the height it rises
depends on the inside diameters of the tubes. The smaller the bore the
higher will the water go up. So with the pores in the wood. They are
very small, and thus the water moves to the greatest heights."

It was now a question of the greatest importance to set up their home at
the most desirable point. The Chiefs, together with John and Blakely,
had numerous conferences with the Professor, on this subject. Many
things had to be taken into consideration.

First: It should be located at a point convenient to all the tribes.

Second: It should be on or near the seacoast.

[Illustration: _Fig. 6. Showing Capillary Attraction._]

Third: Everything else being equal, the most desirable place would be in
a section which had the richest soil.

These considerations were suggested to the Chiefs, and all agreed that
the river separating the land of the Osagas and the Berees would be most
suitable.

"I know a place," said Uraso, "where there is a running water like you
have at the Cataract, and it is a little river that flows into the big
river."

"Does the water go down steep as we had it?"