lutions made by the motor
and propeller. A stop watch took the time; an anemometer measured the
air traveled through; and a counter took the number of revolutions made
by the propellers. The watch, anemometer and revolution counter were all
automatically started and stopped simultaneously. From data thus
obtained we expected to prove or disprove the accuracy of our propeller
calculations.

On November 28, while giving the motor a run indoors, we thought we
again saw something wrong with one of the propeller shafts. On stopping
the motor we discovered that one of the tubular shafts had cracked!

[Illustration]

Immediate preparation was made for returning to Dayton to build another
set of shafts. We decided to abandon the use of tubes, as they did not
afford enough spring to take up the shocks of premature or missed
explosions of the motor. Solid tool-steel shafts of smaller diameter
than the tubes previously used were decided upon. These would allow a
certain amount of spring. The tubular shafts were many times stronger
than would have been necessary to transmit the power of our motor if the
strains upon them had been uniform. But the large hollow shafts had no
spring in them to absorb the unequal strains.

Wilbur remained in camp while I went to get the new shafts. I did not
get back to camp again till Friday, the 11th of December. Saturday
afternoon the machine was again ready for trial, but the wind was so
light a start could not have been made from level ground with the run of
only sixty feet permitted by our monorail track. Nor was there enough
time before dark to take the machine to one of the hills, where, by
placing the track on a steep incline, sufficient speed could be secured
for starting in calm air.

Monday, December 14, was a beautiful day, but there was not enough wind
to enable a start to be made from the level ground about camp. We
therefore decided to attempt a flight from the side of the big Kill
Devil Hill. We had arranged with the members of the Kill Devil Hill Life
Saving Station, which was located a little over a mile from our camp, to
inform them when we were ready to make the first trial of the machine.
We were soon joined by J. T. Daniels, Robert Westcott, Thomas Beachem,
W. S. Dough and Uncle Benny O'Neal, of the station, who helped us get
the machine to the hill, a quarter mile away. We laid the track 150 feet
up the side of the hill on a 9-degree slope. With the slope of the
track, the