One of the most specious of these misconceptions regards the effects of the resistance of the atmosphere upon the figure of the Balloon when rapidly propelled through the air, whereby it is presumed its opposing front will be driven in, and more or less incapacitated from performing the part assigned to it; namely, to cleave its way with the reduced resistance due to its proper form. To obviate, this imagined result, various remedies have been proposed--such as, to construct that part of the machine of more solid materials than the rest, or else (as suggested by one of the most scientific and ingenious of those who have devoted their attention to the theory of aerial navigation), to subject the gaseous contents of the Balloon to such a degree of artificial condensation by compression, as shall supply from within a force equal to that from without; adopting, of course, materials of a stronger texture than those at present in use, for the construction of the balloon. Now the contingency against which it is here sought to provide, and which I grant is a very reasonable one to anticipate, has nevertheless no real existence in practice; at least in such a degree as to render it necessary to have recourse to any particular expedient for its prevention. Taking it for granted that the hypothesis in which it is involved is founded upon a presumed analogy with a Balloon exposed to the action of the wind while in a state of attachment to the earth, I would first observe that the cases in question, however apparently analogous, are in reality essentially dissimilar. In the one case (that where the Balloon is supposed to be attached to the earth) all the _motion_, and consequently all the _momentum_, is in the air; in the other case (where the Balloon is supposed to be progressive), it is in the constituent particles of the machine itself and of its gaseous contents. And this momentum, which is ever proportioned to the rate of its motion, and, consequently, to the amount of resistance it experiences, is amply sufficient to secure the preservation of the form of its opposing front, however partially distended, and whatever the velocity with which it might happen to be endowed. Independently, however, of this corrective principle, another, equally efficacious is afforded in the buoyant power of the included gas, which, occupying all the upper part of the Balloon so long as it is in a condition to sustain itself in the air, and generally extending to its whole capacity, presses from within with a force far greater than any it could experience from the external impact of the atmosphere, and sufficiently resists any impression from that quarter which might tend to impair its form. To what extent this is effective, will appear more clearly when we observe that in any balloon inflated, it is the _sides_ of the distended globe that bear out the weight of the appended cargo, through the intervention of the network; a weight only limited by the