ubt.

"Now," exclaimed Grant, "the next thing to do is to measure off a
distance due north from here."

"Here's your tape measure," laughed John, offering his shoe to Grant.
"That's exactly ten inches long. I'll take my oath to that."

"Let's see," mused Grant. "We want to measure a hundred feet from here
and the shoe is ten inches long. How are we going to figure that out?"

"That's easy enough," exclaimed John. "You do it this way: there are
twelve inches in a foot, of course, and in one hundred feet there would
be one hundred times twelve, or twelve hundred. Now the shoe is ten
inches long, so you divide twelve hundred by ten, which is--"

"One hundred and twenty," said Grant quickly.

"Right," exclaimed John. "In other words, we want to measure a distance
one hundred and twenty times the length of my shoe due north from here."

"Go ahead and do it," urged George. "I'll do it myself."

"You see to it that we keep going straight north," advised Grant. "That
is one of the most important things of all."

"That suits me," said George. "Start your measurements."

The course led off across the sandy beach towards a little clump of pine
trees. Placing the toe of John's shoe close up against the spot on
shark's rock that was their starting place, Grant began to measure. With
a small stick he marked the place to which the heel of the shoe extended
and then repeated the operation, using the marker for a starting-point.
George kept close watch with his compass to see that the correct
direction was being followed.

It was slow work and arduous. Everybody was on his hands and knees
keeping careful watch of all the operations. The sun was hot and in some
places sharp stones or bits of coral were mixed in with the sand so that
more than one of the little party soon had bleeding knees and hands as a
result. No one seemed to mind or even to notice these discomforts,
however. The task they were engaged in was so interesting and absorbing
to them that they paid scant attention to anything else.

"Be sure to keep track of the number of times we have measured, Fred,"
reminded Grant. "We don't want any slip-up, you know."

"Don't worry about that," said Fred confidently. "Every time you shift
that shoe I make a mark on this page from George's diary. When there are
five marks made I cross them off."

"How many so far?" inquired John.

"Seventy," replied Fred after a rapid calculation. "Fifty more to go."

"Don't hurry," w