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Robur the Conqueror

Chapter 3. A Visitor Is Announced
The many experiments made during this last quarter of the nineteenth century
have given considerable impetus to the question of guidable balloons. The cars
furnished with propellers attached in 1852 to the aerostats of the elongated form
introduced by Henry Giffard, the machines of Dupuy de Lome in 1872, of the
Tissandier brothers in 1883, and of Captain Krebs and Renard in 1884, yielded
many important results. But if these machines, moving in a medium heavier than
themselves, maneuvering under the propulsion of a screw, working at an angle to
the direction of the wind, and even against the wind, to return to their point of
departure, had been really "guidable," they had only succeeded under very
favorable conditions. In large, covered halls their success was perfect. In a calm
atmosphere they did very well. In a light wind of five or six yards a second they
still moved. But nothing practical had been obtained. Against a miller's wind--
nine yards a second--the machines had remained almost stationary. Against a
fresh breeze--eleven yards a second--they would have advanced backwards. In
a storm--twenty-seven to thirty-three yards a second--they would have been
blown about like a feather. In a hurricane--sixty yards a second--they would have
run the risk of being dashed to pieces. And in one of those cyclones which
exceed a hundred yards a second not a fragment of them would have been left. It
remained, then, even after the striking experiments of Captains Krebs and
Renard, that though guidable aerostats had gained a little speed, they could not
be kept going in a moderate breeze. Hence the impossibility of making practical
use of this mode of aerial locomotion.
With regards to the means employed to give the aerostat its motion a great deal
of progress had been made. For the steam engines of Henry Giffard, and the
muscular force of Dupuy de Lome, electric motors had gradually been
substituted. The batteries of bichromate of potassium of the Tissandier brothers
had given a speed of four yards a second. The dynamo-electric machines of
Captain Krebs and Renard had developed a force of twelve horsepower and
yielded a speed of six and a half yards per second.
With regard to this motor, engineers and electricians had been approaching more
and more to that desideratum which is known as a steam horse in a watch case.
Gradually the results of the pile of which Captains Krebs and Renard had kept
the secret had been surpassed, and aeronauts had become able to avail
themselves of motors whose lightness increased at the same time as their
power.
In this there was much to encourage those who believed in the utilization of
guidable balloons. But yet how many good people there are who refuse to admit
the possibility of such a thing! If the aerostat finds support in the air it belongs to
the medium in which it moves; under such conditions, how can its mass, which
offers so much resistance to the currents of the atmosphere, make its way
against the wind?
In this struggle of the inventors after a light and powerful motor, the Americans
had most nearly attained what they sought. A dynamo-electric apparatus, in
 
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