FLYING MACHINES. 
9 
the following description of the steam engine, which was given 
in the Eeport upon the Exhibition published by the Aeronautical 
Society : ‘‘ The steam engine does not differ from an ordinary 
one, except in the precautions to ensure lightness. The two- 
inch cylinder is of very thin brass tube ; the covers, flanges, and 
glands are also as light as can be made, consistently with 
strength ; the ports and passages are in one separate piece, 
screwed on ; the piston-rod passes through each end of the 
cylinder, and by means of long connecting rods, works in op- 
posite directions two cranks, fitted to the axes of two four-bladed 
screws, three feet in diameter ; two light bars extend from the 
crank-shaft down each side of the cylinder : these sustain the 
thrust of the piston, and a framing is thus almost dispensed 
with. The boiler consists of a number of inverted cones, made 
of very thin sheet copper, with the joints soldered with silver 
solder. Each cone is closed wdth a hemispherical cap. The 
cones are placed in parallel rows ; the bottom ends, or apexes, 
of the series are all connected together by water-tubes ; and 
from the hemispherical tops a small steam pipe conveys the 
steam away to a cylindrical chamber above the system : this is 
set in the smoke-box, and serves as a super-heater, and the 
steam is quite dried therein. The cones are not liable to prime, 
as the water surface for the escape of the steam is extensive, 
and the steam rises clear from the generating surfaces. The 
fire space between the bases being large and free, this form of 
boiler is particularly well adapted for burning liquid fuels. 
The question may be asked. Is there not some hazard in em- 
ploying metal almost as thin as paper for sustaining pressures 
exceeding 100 lbs. per square inch ? But it is well known that 
in the so-termed ‘ tubulous ’ boilers, to which class this one 
belongs, if a rupture takes place in one of the elements, a 
gradual and harmless escape of water and steam is the only 
consequence ; this empties the boiler by degrees, and at the same 
time ends the danger by extinguishing the fire, thus differing in 
character to the explosion of a boiler, whose strength depends 
upon the external shell, the fracture of which causes instant 
destruction, both to itself and all within its vicinity.” 
The cylinder is two inches in diameter, stroke three inches, 
boiler pressure 100 lbs, per square inch. The engine makes 
300 revolutions per minute. In three minutes after lighting 
the fuel, the pressure was 30 lbs. ; in five minutes, 50 lbs. ; and 
in seven minutes it attained its full working pressure of 100 lbs., 
driving two four-bladed screw propellers, three feet in diameter, 
at 300 revolutions per minute. 
In an article entitled Swimming or Flying,” contributed to 
the Times, and published April 9, 1868, signed The Apteryx,” 
the author comments upon the possibility of man’s sustaining 
