sustaining power of the machine itself, and in the case of the great Vauxhall or Nassau Balloon, amounting to more than two tons, and consequently pressing with a force far exceeding any that could arise from the impact of the air at any rate of motion it could ever be expected to accomplish. And this statement, which represents the theoretical view of the question, is fully borne out by the real circumstances of the case as they appear in practice. So far from justifying the apprehensions of those who conceive that the _front_ of the Balloon would be disfigured by its compulsory progression through the air, the result is exactly the reverse; the only tendency to derangement of form displaying itself in the part _behind_, where the rushing in of the atmospheric medium to fill the place of the advancing body (in the nature of an _eddy_, as it is termed in water), might and no doubt would, to some extent (though perhaps but slightly) affect the figure of that part, in a manner, however, calculated rather to aid than to impair the general design in view, Another error of more universal prevalency, because of a more superficial character, regards the condition of the Balloon as affected by the currents of air, in and through which it might have to be propelled. The arguments founded upon such a view of the case, generally assume some such form as the following--"It is true you can accomplish such or such a rate of motion; but that is only in a room, with a calm atmosphere, or with a favourable current of wind. In the open air, with the wind at the rate of twenty or thirty miles an hour, your feeble power would be of no avail. You could never expect to direct your course _against_ the wind, and if you were to attempt it and the wind were strong, you would inevitably be blown to pieces by the force of the current." Now this argument is equally nought with the preceding. The condition of the Balloon, as far as regards the exercise of its propulsive powers, is precisely the same whether the wind be strong or gentle, with it or against it. In neither case would the Balloon experience any opposition or resistance to its progress but what _itself_, by its _own_ independent motion, created; and that opposition or resistance would be exactly the same in whatever direction it might be sought to be established. The Balloon, passively suspended in the air, without the exercise of a propulsive power, experiences no effects whatever from the motion of the atmosphere in which it is carried, however violent; and the establishment of such a propulsive power could never subject it to more than the force itself, with which it was invested. The _way_ which the Balloon so provided would make through the air would always be the same, in whatever direction, or with whatever violence the wind might happen to blow; and the condition of the Balloon would always be the same that was due to its _own independent_ rate of motion,