of the War
period, and the later British rigids developed yet more.

Before passing on to consideration of the petrol-driven type of engine,
it is necessary to accord brief mention to the dirigible constructed in
1884 by Gaston and Albert Tissandier, who at Grenelle, France, achieved
a directed flight in a wind of 8 miles an hour, obtaining their power
for the propeller from 1 1/3 horse-power Siemens electric motor, which
weighed 121 lbs. and took its current from a bichromate battery weighing
496 lbs. A two-bladed propeller, 9 feet in diameter, was used, and
the horse-power output was estimated to have run up to 1 1/2 as the
dirigible successfully described a semicircle in a wind of 8 miles an
hour, subsequently making headway transversely to a wind of 7 miles
an hour. The dirigible with which this motor was used was of the
conventional pointed-end type, with a length of 92 feet, diameter of 30
feet, and capacity of 37,440 cubic feet of gas. Commandant Renard, of
the French army balloon corps, followed up Tissandier's attempt in
the next year--1885--making a trip from Chalais-Meudon to Paris and
returning to the point of departure quite successfully. In this case the
motive power was derived from an electric plant of the type used by
the Tissandiers, weighing altogether 1,174 lbs., and developing
9 horsepower. A speed of 14 miles an hour was attained with this
dirigible, which had a length of 165 feet, diameter of 27 feet, and
capacity of 65,836 cubic feet of gas.

Reverting to the petrol-fed type again, it is to be noted that
Santos-Dumont was practically the first to develop the use of the
ordinary automobile engine for air work--his work is of such importance
that it has been considered best to treat of it as one whole, and
details of the power plants are included in the account of his
experiments. Coming to the Lebaudy brothers and their work, their engine
of 1902 was a 40 horse-power Daimler, four-cylindered; it was virtually
a large edition of the Daimler car engine, the arrangement of the
various details being on the lines usually adopted for the standard
Daimler type of that period. The cylinders were fully water-jacketed,
and no special attempt toward securing lightness for air work appears to
have been made.

The fining down of detail that brought weight to such limits as would
fit the engine for work with heavier-than-air craft appears to have
waited for the brothers Wright. Toward the end of 1903 they f