ter
of 16.7 feet, the power plant being a 7 horse-power Buchet motor.
Santos-Dumont sat on a bicycle saddle fixed to the long bar suspended
under the machine, which also supported motor propeller, ballast; and
fuel. The experiment of placing the propeller at the stem instead of at
the stern was tried, and the motor gave it a speed of 100 revolutions
per minute. Professor Langley witnessed the trials of the machine, which
proved before the members of the International Congress of Aeronautics,
on September 19th, that it was capable of holding its own against a
strong wind.

Finding that the cords with which his dirigible balloon cars were
suspended offered almost as much resistance to the air as did the
balloon itself, Santos-Dumont substituted piano wire and found that the
alteration constituted greater progress than many a more showy device.
He altered the shape and size of his No. 4 to a certain extent and
fitted a motor of 12 horse-power. Gravity was controlled by shifting
weights worked by a cord; rudder and propeller were both placed at the
stern. In Santos-Dumont's book there is a certain amount of confusion
between the No. 4 and No. 5 airships, until he explains that 'No. 5'
is the reconstructed 'No. 4.' It was with No. 5 that he won the
Encouragement Prize presented by the Scientific Commission of the Paris
Aero Club. This he devoted to the first aeronaut who between May and
October of 1900 should start from St Cloud, round the Eiffel Tower,
and return. If not won in that year, the prize was to remain open the
following year from May 1st to October 1st, and so on annually until
won. This was a simplification of the conditions of the Deutsch Prize
itself, the winning of which involved a journey of 11 kilometres in 30
minutes.

The Santos-Dumont No. 5, which was in reality the modified No. 4 with
new keel, motor, and propeller, did the course of the Deutsch Prize,
but with it Santos-Dumont made no attempt to win the prize until July of
1901, when he completed the course in 40 minutes, but tore his balloon
in landing. On the 8th August, with his balloon leaking, he made
a second attempt, and narrowly escaped disaster, the airship being
entirely wrecked. Thereupon he built No. 6 with a cubic capacity of
22,239 feet and a lifting power of 1,518 lbs.

With this machine he won the Deutsch Prize on October 19th, 1901,
starting with the disadvantage of a side wind of 20 feet per second. He
reached the Eiffel Tower in