10 
rOPULAll SCIENCE EEVIEW. 
himself by his own muscular exertion, and especially refers to 
Mr. Charles Spencer’s assertion that he could not only effect 
this feat, but that he could sustain flight for several yards. 
In opposition to this assertion, he says A gymnast who lifts 
weights, and who has supported his owh weight on his arms, on 
wide-set parallel bars, must conclude that the feat announced 
for June is simply impossible, for no acrobat could lift and 
sustain himself in the attitude of a spread eagle, by beating the 
air long enough to move the distance. If this aeronaut flaps at 
all, he will come to grief, like the sage in Easselas, and like all 
others who have tried flying with artificial wings.” 
]\Ir. Spencer is acknowledged to be one of the best teachers 
of gymnastics in this country, and he is himself no mean per- 
former. His experience upon the trapeze induced in him the 
belief that it would not require so much proportion of plane 
surface to support a given weight as is generally supposed. 
He accordingly constructed an apparatus, and by its means 
he avers that he has proved, that 110 square feet properly dis- 
posed, is sufficient to sustain 158 lbs. weight. With such an 
apparatus, composed of plane and wings, he states, that running 
down a small incline in the open air, and jumping from the 
ground, lie has by the action of the wings, sustained flight to 
the extent of 1 20 feet. 
The framework of this apparatus, exhibited at the Crystal 
Palace, was a marvel of lightness and strength, composed of 
steel umbrella wires and wicker work. In attempting to im- 
prove upon a previously constructed design, the material with 
which he covered it, was found to be too fragile, but he states 
that on practising in the transept of the Crystal Palace — the 
apparatus being suspended from the roof by a rope — he was 
able to raise himself by the action of the wings. Fig. 3 is 
from a photograph of the apparatus. The tail is here denuded 
of its covering. Length of tail, 18 ft. ; width at the end, 8 ft. ; 
depth of keel at the end, 4 ft. ; weight of tail, 15 lbs. ; area of 
tail, 72 sq. ft. liCngth of wing, 7 ft. ; width at the widest part, • 
4 feet; area, 15 sq. ft.; weight, 1^ lb.; weight of the whole tail, 
15 lbs. ; wings, 3 lbs. = 18 lbs. ; weight of himself, 10 stone, and 
sustaining surface, 1 10 sq. ft. ; total weight of himself and appa- 
ratus, 158 lbs. ; making not quite 1^ lb. to the square foot. 
Owing to the wicker-work — which is made to fit tight round 
the body — causing pain, and otherwise obstructing his move- 
ments, he was un/ible to satisfy the curiosity of the public, and 
In* is now rerf»n.stnicting that portion, and substituting a stronger 
material for the; covering. 
O 
Arroriling to I)e Lucy’s theory of surface in inverse ratio to 
weight, the sustaining surface, instead of being 110 square feet, 
need (»nly have been about 31 sfjuare feet, always supposing - 
