The conditions seem to be these. In order to fly in the air, and steer in a given direction during a given period, it is requisite to take up a buoyancy and a power which shall be greater (and continuously so during the voyage) than needful to sustain its own mechanical weight, together with that of the aeronauts and their various appurtenances; and as much also in excess of these requisitions as shall overcome the adverse action of the wind upon the resisting surface presented by the machine. At present no such power is known which can be used in combination with a balloon, or other gas machine. If we could condense electricity, then the thing might be done; other subtle powers may also be discovered with the progress of science, but we must wait for them before we can fairly make definite voyages in the air, and reduce human flying to a practical utility, or a safe and rational pleasure. MY NOVEL; OR, VARIETIES IN ENGLISH LIFE.[14] BOOK VIII.--INITIAL CHAPTER. THE ABUSE OF INTELLECT. There is at present so vehement a flourish of trumpets, and so prodigious a roll of the drum, whenever we are called upon to throw up our hats, and cry "Huzza" to the "March of Enlightenment," that, out of that very spirit of contradiction natural to all rational animals, one is tempted to stop one's ears, and say, "Gently, gently; LIGHT is noiseless; how comes 'Enlightenment' to make such a clatter? Meanwhile, if it be not impertinent, pray, where is enlightenment marching to?" Ask that question of any six of the loudest bawlers in the procession, and I'll wager ten-pence to California that you get six very unsatisfactory answers. One respectable gentleman, who, to our great astonishment, insists upon calling himself a "slave," but has a remarkably free way of expressing his opinions, will reply--"Enlightenment is marching toward the nine points of the Charter." Another, with his hair _à la jeune France_, who has taken a fancy to his friend's wife, and is rather embarrassed with his own, asserts that Enlightenment is proceeding toward the Rights of Women, the reign of Social Love, and the annihilation of Tyrannical Prejudice. A third, who has the air of a man well to do in the middle class, more modest in his hopes, because he neither wishes to have his head broken by his errand-boy, nor his wife carried off to an Agapemoné by his apprentice, does not take Enlightenment a step further than a siege on Debrett, and a cannonade on the Budget. Illiberal man! the march that he swells will soon trample _him_ under foot. No one fares so ill in a crowd as the man who is wedged in the middle. A fourth, looking wild and dreamy, as if he had come out of the cave of Trophonius, and who is a mesmeriser and a mystic, thinks Enlightenment is in full career toward the good old days of alchemists and necromancers. A fifth, whom one might take for a Quaker, asserts that the march of Enlightenment is a crusade for