“Well, Ned, I repeat it with a conviction resting on the logic of facts. I believe in the existence of a mammal power fully organised, belonging to the branch of vertebrata, like the whales, the cachalots, or the dolphins, and furnished with a horn of defence of great penetrating power.”
“Hum!” said the harpooner, shaking his head with the air of a man who would not be convinced.
“Notice one thing, my worthy Canadian,” I resumed. “If such an animal is in existence, if it inhabits the depths of the ocean, if it frequents the strata lying miles below the surface of the water, it must necessarily possess an organisation the strength of which would defy all comparison.”
“And why this powerful organisation?” demanded Ned.
“Because it requires incalculable strength to keep one’s self in these strata and resist their pressure. Listen to me. Let us admit that the pressure of the atmosphere is represented by the weight of a column of water thirty-two feet high. In reality the column of water would be shorter, as we are speaking of sea water, the density of which is greater than that of fresh water. Very well, when you dive, Ned, as many times thirty-two feet of water as there are above you, so many times does your body bear a pressure equal to that of the atmosphere, that is to say, 15 lbs. for each square inch of its surface. It follows, then, that at 320 feet this pressure = that of 10 atmospheres, of 100 atmospheres at 3200 feet, and of 1000 atmospheres at 32,000 feet, that is, about 6 miles; which is equivalent to saying that if you could attain this depth in the ocean, each square three-eighths of an inch of the surface of your body would bear a pressure of 5600 lbs. Ah! my brave Ned, do you know how many square inches you carry on the surface of your body?”
“I have no idea, Mr. Aronnax.”
“About 6500; and, as in reality the atmospheric pressure is about 15 lbs. to the square inch, your 6500 square inches bear at this moment a pressure of 97,500 lbs.”
“Without my perceiving it?”
“Without your perceiving it. And if you are not crushed by such a pressure, it is because the air penetrates the interior of your body with equal pressure. Hence perfect equilibrium between the interior and exterior pressure, which thus neutralise each other, and which allows you to bear it without inconvenience. But in the water it is another thing.”
“Yes, I understand,” replied Ned, becoming more attentive; “because the water surrounds me, but does not penetrate.”