Many difficulties beset explorers in wild countries. Much time has to be devoted to the journey; transport of supplies, hostility of natives, progress through jungles, marshes, and rivers impede the traveller. Long sojourns and hard work in hot and unhealthy climates, or extreme cold, all present great difficulties. There is, however, one high road which leads unobstructed to all parts — the air. An aeronaut, seated in the car of a balloon, floats along above all impediments and obstructions, travelling day and night at the speed of the wind, and with an extensive view of all the country below. But there are two practical difficulties to be overcome. First, the ordinary free balloon must travel wherever the wind chooses to take it, and that may be in any but the desired direction; secondly, no free balloon has as yet ever remained up longer than a day or two.