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
towards 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 gun powder on board,
without either saltpetre, 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?