It was not until 1884 that M. Gaston Tissandier constructed a dirigible
in any way worthy of the name. It was operated by a motor driven by
a bichromate of soda battery. The motor weighed 121 lbs. The cells
held liquid enough to work for 2-1/2 hours, generating 1-1/3 horse
power. The screw had two arms and was over nine feet in circumference.
Tissandier made some successful flights.

The first dirigible balloon to return whence it started was that known
as _La France_. This airship was also constructed in 1884. The
designer was Commander Renard of the French Marine Corps assisted by
Captain Krebs of the same service. The length of the envelope was 179
feet, its diameter 27-1/2 feet. The screw was in front instead of
behind as in all others previously constructed. The motor which weighed
220-1/2 lbs. was driven by electricity and developed 8-1/2 horse power.
The propeller was 24 feet in diameter and only made 46 revolutions to
the minute. This was the first time electricity was used as a motor
force, and mighty possibilities were conceived.

In 1901 a young Brazilian, Santos-Dumont, made a spectacular flight.
M. Deutch, a Parisian millionaire, offered a prize of $20,000 for the
first dirigible that would fly from the Parc d'Aerostat, encircle the
Eiffel Tower and return to the starting point within thirty minutes,
the distance of such flight being about nine miles. Dumont won the
prize though he was some forty seconds over time. The length of his
dirigible on this occasion was 108 feet, the diameter 19-1/2 feet. It
had a 4-cylinder petroleum motor weighing 216 lbs., which generated
20 horse power. The screw was 13 feet in diameter and made three hundred
revolutions to the minute.

From this time onward great progress was made in the constructing of