n the form of a wedge, a pulley, a wheel and axle, an
inclined plane, a screw or a lever. All these forms do the same thing as
the simple lever; and what sort of mechanism could be made without some
of these elements? The row-lock is simply the fulcrum for the oar, is it
not? When Archimedes discovered the principles of the lever, he was so
excited that he declared he could move the earth if he could find a
fulcrum."

A careful examination of the notched gunwale showed conclusively that it
had been used to a considerable extent. George sat and pondered over
this. "I am sure we never used the boat enough with the oars to wear it
in this way. Had you examined this when you said that the boat had not
been long at the point where we found it?"

"No," answered the Professor; "I simply remembered that on the day you
lost it the wind was blowing to the west, and as you found it to the
east of the cliffs, I inferred it must have been carried around since
that time."

"It is evident then that the people who used this boat live to the west
of us?"

"That is my only conclusion."

"Then you think the fire in the forest, and the light which we saw that
night beyond the West River, were made by those people?"

"I am sure the fire we saw was made by savages, but I am not so certain
about the lights having been made by them."

Harry looked at the Professor, and then at George, and slowly shook his
head. "Wasn't it lucky we didn't meet them when we made our trip to the
river?"

That evening the inevitable subject of their forthcoming voyage was
again discussed, and to the surprise of the boys, the Professor urged
delay. His reasons were expressed as follows:

"While we have had some very severe storms of the kind which may be
expected, we are not sure that the weather is yet fully settled. That is
the only reason I urge delay. If, on the other hand, we should decide to
take an overland journey, we could set out at once."

Harry was opposed to taking another trip by land. "We have really found
out more by the water route than going by land. For that reason it would
be well for us to make at least one adventure by sea."

These arguments prevailed in the minds of all, and while it would take
some time before all preparations could be made, all were happy at the
thought that when they did undertake the journey something definite
would be learned to clear up a few of the mysteries of Wonder Island.

The Professor did find some