egular business to undertake the building of such a motor for us; but
one company replied that they had motors rated at 8 horse-power,
according to the French system of ratings, which weighed only 135
pounds, and that if we thought this motor would develop enough power for
our purpose they would be glad to sell us one. After an examination of
the particulars of this motor, from which we learned that it had but a
single cylinder of 4-inch bore and 5-inch stroke, we were afraid it was
much over-rated. Unless the motor would develop a full 8
brake-horsepower, it would be useless for our purpose.

Finally we decided to undertake the building of the motor ourselves. We
estimated that we could make one of four cylinders with 4-inch bore and
4-inch stroke, weighing not over two hundred pounds, including all
accessories. Our only experience up to that time in the building of
gasoline motors had been in the construction of an air-cooled motor,
5-inch bore and 7-inch stroke, which was used to run the machinery of
our small workshop. To be certain that four cylinders of the size we had
adopted (4" x 4") would develop the necessary 8 horse-power, we first
fitted them in a temporary frame of simple and cheap construction. In
just six weeks from the time the design was started, we had the motor on
the block testing its power. The ability to do this so quickly was
largely due to the enthusiastic and efficient services of Mr. C. E.
Taylor, who did all the machine work in our shop for the first as well
as the succeeding experimental machines. There was no provision for
lubricating either cylinders or bearings while this motor was running.
For that reason it was not possible to run it more than a minute or two
at a time. In these short tests the motor developed about nine
horse-power. We were then satisfied that, with proper lubrication and
better adjustments, a little more power could be expected. The
completion of the motor according to drawing was, therefore, proceeded
with at once.

[Illustration]

While Mr. Taylor was engaged with this work, Wilbur and I were busy in
completing the design of the machine itself. The preliminary tests of
the motor having convinced us that more than 8 horse-power would be
secured, we felt free to add enough weight to build a more substantial
machine than we had originally contemplated.

* * * * *

For two reasons we decided to use two propellers. In the first place w