ON THE PROGRESS OF AERONAUTICS. 
371 
another, ignoring Mr. Stringfellow’s light engine, which then 
gained the prize, he commenced to design another which he 
deemed more suitable for his object. This was to actuate four 
driving-wheels, ten inches in diameter, to act in their turn 
upon two aero-plane wheels, six feet in diameter, by frictional 
gearing on the periphery. The aero-plane wheels had each 
twelve light wooden planes fitted to them, something like the 
screw-propeller, but with the important difference that the 
pitch was variable at every portion of the revolution. His 
theory was, that the action of these planes in their revolution 
through the air was a perfect mechanical imitation of the 
action of a bird’s wing in the various positions that its surface 
assumes during the progress of flight, giving, as it does, an 
upward and forward thrust continually, without any downward 
force from the air on any of the aero-planes. The whole 
apparatus was placed upon wheels. 
The steam-engine was contained iu a case 27 inches by 27-J 
inches by 7-J- inches. The diameter of its cylinder was 2^- 
inches, length of stroke 3 inches. The generating tabes con- 
tained a surface of eight square feet, and in these tubes the water 
circulated with very great rapidity, and thereby utilised the 
heat in the very best manner. There was literally no framing* 
to the engine itself, as the driving-axle ran in a tube which 
passed through the steam-chest. The steam was cut off at 
half-stroke by the slide-valve, and with a pressure of from 120 
to 160 lbs. to the square inch, and 536 revolutions per minute, 
it might fairly be called a 3-horse-power engine. The fuel 
used was methylated spirits under pressure, which produced 
blow-pipe flames. 
With regard to the form of the so-called “ aerial steamer,” 
which was tried in March 1874, we may say that the engine 
was fixed about four feet from the ground, on a framework which 
also held the lamps. Other frames, extended from this on each 
side, take the axles of the 6-feet driving-wheels. These axles 
were 3 feet 3 inches in length and 1^ inch in diameter, made 
of drawn brass tube, and very light and strong. An aero-plane 
of 50 square feet surface was fitted in front, and one of 64 
square feet behind. 
These were inclined at an angle of 10° from the horizontal; 
and Mr. Moy calculated that if the whole could be driven on the 
ground at thirty-five miles an hour, it would encounter a pressure 
from the atmosphere sufficient to support the whole weight of 
the machine, which amounted with its engine, fuel, &c., to 
214 lbs. The driving-surface of the revolving aero-planes was 
equal to 60 square feet. 
Before running the 66 aerial steamer ” round the central 
fountain at the Crystal Palace, Mr. Moy took steps to test the 
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