2 22                            FLYING   MACHINES.
published in 1680, and it doubtless has had many stanch advo-
cates in later times ; but the writer maintains that this is the
first practical demonstration that a machine can and does fly by
the simple (vertical) flapping of wings ; the feathering, tilting,
twisting, trochoiding, or whatever it may be called, being solely
effected by torsional stress on the wing arms.
The combination of Borelli's views with the results of work
recorded in your proceedings (Royal Society) has swept away
such a mass of tackle from the machine that its construction
becomes a ridiculously simple matter. The engine of tbe
model, of course, retains its precedence as the most important
part, and by continuous effort the number of pieces and the
difficulties of construction have been so reduced that it is pos-
sible to make them by the gross at a cost that cannot exceed
five shillings each ($1.25). For instance, the cylinder, usually
the most expensive portion of an engine, can be produced with
the ease and celerity of a tin can.
It might be said that this flying machine is not on the principle
enunciated by Borelli, because the wings are not continuous
from their tip to the body. But this arrangement is only a de-
vice to enable the wing tips to act on the required quantity of
air with less spread ; it may possibly be one of those variations
which make all the difference between success and failure.
These wings are also distinctly double-acting, and it is not
quite clear that birds' wings thrust during the up-stroke ; but,
as previously stated, the question as to the exact movement ot
a bird's wing is merely straw-splitting, when wc have a mech-
anism that actually flies and is manifestly imperfect in its pres-
ent mechanical details.
This machine flew 368 ft., with the expenditure (as cor-
rected by M. Hargrave) of 870 foot-pounds of energy. It
weighed 2.53 lbs., and the sustaining body plane measured
14.78 sq. ft., while the two wings measured 1.50 sq. ft. in
area, making a total of 16.28 sq. ft., or, say, 6 43 sq. ft.
per pound.
London Engineering, in its issue of December 26, 1890,
gives the following description of the machine :
The compressed air is stored in a tube which forms the back-
bone of the whole construction. This tube is 2 in. in diameter,
48+; in. long, and has a capacity of 144.6 cub. in. Its weight is
19.5 oz., and the working pressure is 230 lbs. per square inch.
The engine cylinder has a diameter of i\ in. and a stroke of
li in., while the total weight of the engine is only 6£ oz. The
piston-rod is made fast lo the end of the backbone, and the
cylinder moves up and down over the piston. Two links con-
nect the cylinder to the Canadian red pine rods which carry the
wings. The air is admitted to the cylinder and exhausted by
means of a valve worked by tappets. The period of admission
continues through the entire stioke. The cylinder and receiver
ends are pressed, and the piston is made of vulcanite, with a
leather cup ring for packing.