Chapter 10 Former Experiments.—The Doctor's Five Recept-acles.—The Gas Cylinder.— The Calorifere.—The System of Manoeuvring.—Success certain. "The attempt has often been made, gentlemen," said the doc-tor, "to rise and descend at will, without losing ballast or gas from the balloon. A French aeronaut, M. Meunier, tried to ac-complish this by compressing air in an inner receptacle. A Belgian, Dr. Van Hecke, by means of wings and paddles, obtained a vertical power that would have sufficed in most cases, but the practical results secured from these experiments have been insignificant. "I therefore resolved to go about the thing more directly; so, at