understand me.

"Well, then," I continued, "you see that we shall have no difficulty as
to the dam. Then, as to the wheel, it will be a simple one of not more
than four feet diameter, presented vertically to what I may term the
water-spout, so that its axle, which will have a crank in it, will work
the saw direct; thus, avoiding toothed wheels and cogs, we shall avoid
friction, and, if need be, increase the speed easily, d'you see?"

"Bon, monsieur--good, good," exclaimed Coppet, becoming quite
enthusiastic in his appreciation of my plans.

"Of course," I continued, "the saw can easily be fitted to a frame, and
a very simple contrivance can be made to drive along the larger frame
that will carry the logs to be sawn; but these are trifling matters of
detail which you and I will work out at our leisure, Dumont."

"Oui, monsieur, oui," replied the blacksmith, with tighter knitted
brows, and with a readiness of assent which I do believe the good fellow
would have accorded if I had proposed to fit a new axis to the world.

"There is only one thing that troubles me," said I: "how are we to gauge
or estimate the force of our water-spout so as to regulate our mill when
made? Do you understand such matters--the measurement of force--
Coppet?"

The carpenter shook his head.

"That's unfortunate. Do you, Dumont?"

"Non, Monsieur."

"H'm! I'm sadly ignorant on the point myself," I continued. "Of course
I know that so many cubic feet of water will exert a certain pressure,
but then I don't know what that certain pressure is, nor how to find out
how many cubic feet our somewhat irregular dam will contain. Nor do I
know precisely the strength of the material required in the dam to
resist the water."

Dumont humbly suggested here that we could at all events act on the
principle that guided Adam and Eve in the formation of their first
water-mill, and find out by experiment. And Coppet said that we could
get over the difficulty about the strength of materials by making
everything ten times stronger than was required.

"You are right lads," said I, much amused with the earnest manner in
which they gave the advice. "Now let us go at it without delay, so that
we may get into working order before the frost stops us."

We set to with enthusiasm, and progressed with our labour much faster
than I had expected. The natural basin, to which I have referred, lay
just below a ledge of rock over which the rivulet flowed into it