“It is actually a manometer. But by communication with the water, whose external pressure it indicates, it gives our depth at the same time.” “And these other instruments, the use of which I cannot guess?” “Here, Professor, I ought to give you some explanations. Will you be kind enough to listen to me?” He was silent for a few moments, then he said— “There is a powerful agent, obedient, rapid, easy, which conforms to every use, and reigns supreme on board my vessel. Everything is done by means of it. It lights it, warms it, and is the soul of my mechanical apparatus. This agent is electricity.” “Electricity?” I cried in surprise. “Yes, sir.” “Nevertheless, Captain, you possess an extreme rapidity of movement, which does not agree with the power of electricity. Until now, its dynamic force has remained under restraint, and has only been able to produce a small amount of power.” “Professor,” said Captain Nemo, “my electricity is not everybody’s. You know what sea-water is composed of. In a thousand grammes are found 96½ per cent. of water, and about 2-2/3 per cent. of chloride of sodium; then, in a smaller quantity, chlorides of magnesium and of potassium, bromide of magnesium, sulphate of magnesia, sulphate and carbonate of lime. You see, then, that chloride of sodium forms a large part of it. So it is this sodium that I extract from sea-water, and of which I compose my ingredients. I owe all to the ocean; it produces electricity, and electricity gives heat, light, motion, and, in a word, life to the _Nautilus_.” “But not the air you breathe?” “Oh! I could manufacture the air necessary for my consumption, but it is useless, because I go up to the surface of the water when I please. However, if electricity does not furnish me with air to breathe, it works at least the powerful pumps that are stored in spacious reservoirs, and which enable me to prolong at need, and as long as I will, my stay in the depths of the sea. It gives a uniform and unintermittent light, which the sun does not. Now look at this clock; it is electrical, and goes with a regularity that defies the best chronometers. I have divided it into twenty-four hours, like the Italian clocks, because for me there is neither night nor day, sun nor moon, but only that factitious light that I take with me to the bottom of the sea. Look! just now, it is ten o’clock in the morning.” “Exactly.” “Another application of electricity. This dial hanging in front of us indicates the speed of the _Nautilus_. An electric thread puts it in communication with the screw, and the needle indicates the real speed. Look! now we are spinning along with a uniform speed of fifteen miles an hour.” “It is marvelous! And I see, Captain, you were right to make use of this agent that takes the place of wind, water, and steam.” “We have not finished, M. Aronnax,” said Captain Nemo, rising. “If you will follow me, we will examine the stern of the _Nautilus_.”