“I listen.”
“You know as well as I do, professor, that man can live under water, providing he carries with him a sufficient supply of breathable air. In submarine works, the workman, clad in an impervious dress, with his head in a metal helmet, receives air from above by means of forcing-pumps and regulators.”
“That is a diving apparatus,” said I.
“Just so; but under these conditions the man is not at liberty; he is attached to the pump which sends him air through an India-rubber tube, and if we were obliged to be thus held to the Nautilus, we could not go far.”
“And the means of getting free?” I asked.
“It is to use the Rouquayrol apparatus, invented by two of your own countrymen, which I have brought to perfection for my own use, and which will allow you to risk yourself under these new physiological conditions, without any organ whatever suffering. It consists of a reservoir of thick iron plates, in which I store the air under a pressure of fifty atmospheres. This reservoir is fixed on the back by means of braces, like a soldier’s knapsack. Its upper part forms a box in which the air is kept by means of a bellows, and therefore cannot escape unless at its normal tension. In the Rouquayrol apparatus such as we use, two India-rubber pipes leave this box and join a sort of tent which holds the nose and mouth; one is to introduce fresh air, the other to let out the foul, and the tongue closes one or the other according to the wants of the respirator. But I, in encountering great pressures at the bottom of the sea, was obliged to shut my head, like that of a diver, in a ball of copper; and it is to this ball of copper that the two pipes, the inspirator and the expirator, open.”
“Perfectly, Captain Nemo; but the air that you carry with you must soon be used; when it only contains fifteen per cent. of oxygen, it is no longer fit to breathe.”
“Right! But I told you, M. Aronnax, that the pumps of the Nautilus allow me to store the air under considerable pressure; and on those conditions, the reservoir of the apparatus can furnish breathable air for nine or ten hours.”
“I have no further objections to make,” I answered. “I will only ask you one thing, captain—how can you light your road at the bottom of the sea?”
“With the Ruhmkorff apparatus, M. Aronnax; one is carried on the back, the other is fastened to the waist. It is composed of a Bunsen pile, which I do not work with bichromate of potash, but with sodium. A wire is introduced which collects the electricity produced, and directs it toward a particularly made lantern. In this lantern is a spiral glass which contains a small quantity of carbonic gas. When the apparatus is at work, this gas becomes luminous, giving out a white and continuous light. Thus provided, I can breathe and I can see.”
“Captain Nemo, to all my objections you make such crushing answers that I dare no longer doubt. But if I am forced to admit the Rouquayrol and Ruhmkorff apparatus, I must be allowed some reservations with regard to the gun I am to carry.”
“But it is not a gun for powder,” answered the captain.
“Then it is an air-gun.”
“Doubtless! How would you have me manufacture gunpowder on board, without either saltpeter, sulphur, or charcoal?”
“Besides,” I added, “to fire under water in a medium eight hundred and fifty-five times denser than the air, we must conquer very considerable resistance.”
“That would be no difficulty. There exist guns, according to Fulton, perfected in England by Philip Coles and Burley, in France by Furcy, and in Italy by Landi, which are furnished with a peculiar system of closing, which can fire under these conditions. But I repeat, having no powder, I use air under great pressure, which the pumps of the Nautilus furnish abundantly.”
“But this air must be rapidly used?”
“Well, have I not my Rouquayrol reservoir, which can furnish it at need? A tap is all that is required. Besides, M. Aronnax, you must see yourself that during our submarine hunt we can spend but little air and but few balls.”