“Just so. But under these conditions the man is not at liberty; he is attached to the pump which sends him air through a 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 without any organ of the body suffering. It consists of a reservoir of thick iron plates, in which I store the air under a pressure of fifty [v]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 [v]normal tension. In the Rouquayrol apparatus such as we use, two 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 foul, and the tongues close one or the other pipe according to the wants of the [v]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 into this ball of copper that the two pipes, the inspirator and the expirator, open. Do you see?”
“Perfectly, Captain Nemo. But the air that you carry with you must soon be used; when it contains only 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 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 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 [v]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 lantern. In this lantern is a spiral glass which contains a small quantity of carbonic acid 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,” he said.
“Then it is an air-gun?” I asked.