Having accepted the wind for his pilot, our argonaut seeks no improvement upon his aerial raft. Like the bow and arrow, it long ago reached perfection, and, though he may cherish some choice and secret recipe for varnish or be the inventor of an improved valve, he generally builds with a birdlike reliance on instinct and tradition. Gas-bag, netting, concentrating-ring, basket, valve, anchor, drag-rope and exploding cord,--what has the century of ballooning added to its essentials? how can coming centuries improve this perfection of simplicity? Aerial navigation is altogether another thing. A swallow does not rise by displacing a volume of air whose specific gravity is greater than its own, but by using the atmosphere as a fulcrum. Otherwise it must possess a bulk which its tiny wings would be powerless to impel against the opposing breeze. Mr. Grimley, the aeronaut, writing of some experiments he has recently been making at Montreal with an ingenious arrangement of revolving fans invented by two gentlemen of that city, says: "The Cowan and Paje propelling and steering apparatus worked as well as could be expected, but the air will never be navigated by balloons driven by machinery. It is opposed to common sense." Few fully appreciate the extreme mobility of the atmosphere or the intensity of the force which wind exerts on surfaces opposed to its action. A child with a palm-leaf fan can drive a balloon in equilibrium about at will in an atmosphere entirely quiet, while the same balloon, under the impulse of a lively gale, will tear itself loose from the aggregated avoirdupois of all who can lay hands upon it, and wrench great branches from the forest giants over which it skims. Doubtless, to the disheartening influence of a practical knowledge of the real difficulties in the way of aerial navigation is due the fact that the great mass of those who have attempted it have been scientists without practice, or fools without either scientific training or experimental data. However strongly, as devout utilitarians, we may feel it our duty to disapprove, officially, of a class so little necessary to the body politic, aeronauts are interesting talkers, being able, like Shakespeare's Moor, to speak of "most disastrous chances, of _moving_ accidents by flood and field, of antres vast and deserts idle, rough quarries, rocks and hills whose heads touch heaven."