Hydrostatics and pneumatics / [Dionysius Lardner].

  • Dionysius Lardner
Date:
1831
Catalogue details

Licence: Public Domain Mark

Credit: Hydrostatics and pneumatics / [Dionysius Lardner]. Source: Wellcome Collection.

    357/376 (page 341)
    loon, and consequently produce a corresponding decrease in its buoyancy. By analogy, we should infer that the power of as- cending at pleasure would be obtained by being able to supply an increased quantity of gas to the balloon; but this would not be easily practicable; and, accordingly, the power of ascending has been obtained by carrying up sand-bags, or other weights called ballast, by throwing out which the machine is lightened, and caused to ascend; or if from any accidental cause it should be found to fall with dangerous precipitancy, its rate of descent may be retarded by throwing out this ballast. The principal cause of danger attending aeronautical experiments arises from the accidental escape of the gas from the balloon; and it has consequently been a de- sirable object to contrive means, in such cases, for ren- dering the fall of the aeronaut less liable to dangerous effects. With this view, an apparatus has been con- trived, called a parachute. It is usually formed like a large umbrella, which spreads above the car with its concave side presented downwards. The effect of this acting against the air below is, to break the descent, and after a short time the rate of descent becomes uni- form, instead of being, as heavy bodies generally are, accelerated. The magnitude of the parachute may be such, that the rate of descent shall be so slow that no danger is to be apprehended from the concussion at- tending the fall. If, therefore, the aeronaut descend on land, his safety is insured. The subjects of the first experiments with the para- chute were naturally inferior animals. M. Blanchard dropped a dog suspended from a parachute, from the altitude of 6’000 feet above the surface of the earth. A whirlwind interrupted its descent, and carried it above the clouds. The aeronaut soon after met the parachute again; the dog recognised, its master, and expressed his uneasiness and solicitude by barking; another current of air, however, carried him off, and he was lost sight of. The parachute with the dog descended soon after the