88

Classification of the Sciences
88

α, Air-vessels with ascensional power but nonmechanical motors;

β, Air-vessels with ascensional power and mechanical motors;

γ, Air-vessels without ascensional power but with mechanical motors;

δ, Air-vessels with neither ascensional power nor mechanical motors.

1cα. Balloons are of two classes; those which are compressible and are therefore allowed to be open at the bottom, and those which are rigid and taut. A compressible balloon is either a Montgolfier or a gas balloon. A Montgolfier is a cheap and simple affair, usually made of duck or canvass, and ascending only so long as the air remains hot (though in early days fire was carried up) after which the aeronaut[s] descend under a parachute and the balloon is abandoned to be picked up afterward. It is so cheap that there is little temptation to steal it, nor would it be a vast loss if never recovered; but it cannot go far, for ascensions are not made in high winds. A gas-balloon, contrary to popular notions, is the safest thing in the world except in the landing, unless one mounts to a great height. But next to nothing can be seen from it ordinarily and the experience of