20 Meérial Navigation. 
while those beyond open, and let the incumbent air through. Both 
wings being fastened together moveably by the hinges at s, ¢, u, 5 
when the handles are raised up, the axles advance towards the car, 
and when brought down from it, to allow their motion by means of 
the joints Ii, Ji, in the semi-circular rods Gg, Gg. ‘The aéronaut, 
in moving wings on this plan, has a purchase of one half of each 
wing to strike the air beyond the axles, and his own weight suspend- 
ed on the other, the air within, besides the alternate reaction, arising 
from their percussion, which is proportional to the power applied on 
each side of the axles EE, ee. Whether the handles are moved 
upwards or downwards, the wings strike the air equally and con- 
stantly on each side of the car, and alternately on each side of 
their axles, during their motion, and the reaction of the air assists 
so as to move them equally and constantly. The wings being bal- 
anced on their axles and the valves nearly so on their wires, it is evi- 
dent that their weight is no impediment to their motion. Wings of 
any shape and size, being wired, valved, and balanced equally on 
each side of their axles, can be governed and moved by a small 
power or force, and the better and the more effectually as the power 
or force is increased. This principle of a balance can be likewise 
beneficially applied in submarine navigation, either to ascend, de- 
scend, or move forward in the water. In figure 2, when the aéro- 
naut raises the hoop efgh, quickly, all the valves between it, and the 
middles of the flattened shafts I, J, K, L, M, N, O, P, or where the 
upper ends of the braces 1, 2, 3, 4, 5, 6, 7, 8, are moveably hung to 
them, will open and let the neat air through 5 while those be- 
yond will close, air tight, and strike the air to the quick- 
ness of the motion; when he brings the hoop quickly “down, all the 
valves between it sige the middle of the flattened shafts will close air 
tight and strike the air similarly ; while those beyond will open and 
let the incumbent air through. When the hoop is raised, (as all the 
flattened shafts are moveably hung to it,) the upper ends of all the 
braces, (being pee an eneney necge at both =) move inwards 
towards the car, w h ,th 
thus allow the motion of a balance to the are surface we the ring or 
wings. “Th Ii around th 
but one wing. on this construction: This wing ae the air equally 
all around the car, at equal distances, when moved and prevents the 
escape of the air at any part within its circumference. Having de- 
seribed two applications of the principle of a balance to the motion 
