FLYING MACHINES. 
11 
that the surface was effectively disposed, which in Spencer’s 
apparatus may be very properly questioned. 
Want of space, however, precludes any attempt to pursue 
this question further. 
We come now to the description of another machine exhibited, 
the invention and construction of Wm. Gibson, a working man 
of Outram Street, West Hartlepool. 
Dissimilar to either of the former inventions, which respec- 
tively consisted of plane — and plane with wings — this was ex- 
pected to obey the action of the wings alone. 
The mechanical action at the command of the operator was 
intended to be controlled by the downward pressure of each leg 
alternately, assisted by the arms. 
The machine therefore consisted of a framework, to which 
were attached four wings, so that by pressure upon one treadle, 
two flew up feathered, and two descended with an impact upon 
the air, as in Fig. 4, where the two lower wings are in the act 
of ascending. 
In a previously constructed apparatus provided with two 
wings only, Gibson states that a man weighing 10^ stone re- 
peatedly raised himself from the ground from 12 to 18 inches, 
but that he could not sustain himself, because the wings being 
so heavy, he was not able to repeat the stroke. Each wing was 
12 feet long, 1|- feet across at the wider part, and 1 foot at the 
narrower; surface of both wings 37 square^feet ; weight of each 
wing, 10 lbs. ; frame and rods, 21 lbs. ; weight of man, lOJ 
stone ; giving about 5 lbs. to each foot of sustaining surface, a 
condition which severely tests the theory of inverse proportion 
of surface to weight. 
The four-winged contrivance sent to the Crystal Palace was 
found to be too heavy for trial, but the inventor’s enthusiasm 
seems to be quite equal to the construction of another and 
lighter apparatus for further exhibition. 
It must be remarked as an interesting feature in Gibson’s 
apparatus, that the total weight of the man and apparatus, as 
compared with the surface, gives on De Lucy’s theory, about 
38 square feet as the proper sustaining surface, or one foot 
more than it possesses — taking for our calculations, the Austra- 
lian crane, and the theory of inverse proportion with its margin 
of from eight to ten times. 
Experiments can alone determine the true path to success, 
and it is encouraging to find that these are now aiding in the de- 
termination of the question. It is possible that we may shortly 
witness some more advanced attempts, and should they prove to 
be failures in the practical solution of the problem, it will per- 
haps be remembered that previous failure having led to increased 
knowledge, so future success may result from their repetition. 
