On Aérial Navigation. 31 
eause of failure, but the application of the power of one or two 
-men, with very ill appropriated means, to perform what required 
the strength of twice as many horses. With respect to the oblique 
force noticed by your correspondent, I wish to refer him to the 
case of a barge drawn along the centre of a canal by a rope to a 
horse on the bank ;—no power is lost by this mode of draft, but 
what arises from the actual path of the vessel not coinciding with 
the line of its major axis, which slight increase of resistance is 
foreign to the case of a spherical balloon, where simple gravita- 
tion, and not the pressure of a fluid on an oblique plane, is the re- 
straining force. This is best explained by a figure. 
Let A, fig. 1, Plate I. be aballoon. B its car, propelled be- 
yond the centre of suspension by any given power of waftage ; 
draw AC perpendicular, and CB parallel to the horizon; and 
let these lines be in the same ratio to each other as the weight 
of the car is to the propelling power ; then the line AB will re- 
present the whole action of the car upon the balloon. Draw 
AD and BD, respectively, parallel to the two former lines, and 
it becomes evident that the power of the compound force AB, 
will have the same effect as the two forces AD, equal to CB, 
the propelling power, and AC the weight of the car; which 
being just balanced by the floating power that may be repre- 
sented by BD, leaves the balloon to be carried along in its hori- 
zontal path by the same force, as if dragged in the direct line 
of its centre AD. I have been the more particular in my ob- 
servations on this point, because I wish to show that long bal- 
loons filled with hydrogen gas may be made use of at any distance 
above the car they support, which may be found to render them 
safe from the fire of the engine, and yet not be subject to any 
loss of power from the waftage being applied to the car in lieu 
of the balloon. Thirty or forty yards, if necessary, may inter- 
vene between the balloon and top of the chimney of the fire 
which works the engine. Wire-gauze, so celebrated of late for 
preventing the communication even of explosive mixtures of hy- 
drogen with each other, may interpose its magic web to cut off 
any danger in this respect; and as the hydrogen gas balloon 
must (for the sake of firm resistance to the external air, so as to 
preserve the proper form of the prow) be inclosed in one of 
coarser materials, into which common air can be pumped to the 
required density between them, it becomes almost impossible 
that any accident from fire can take place. A flexible leather 
tube and cordage will thus form the only connection between the 
boat and the balloon, The stupendous bulk of such balloons as 
upon calculation appear capable of being made to convey con- 
siderable burthens with the requisite degree of speed, forms the 
chief 
