"Well, a square yard of air weighs two pounds and a half, but a square yard of water weighs two thousand pounds. Now, can you calculate the weight of the water that is on your back and pressing on your sides when you swim?"
"No, I cannot."
"You are not sufficiently up in arithmetic to do that, Willis?"
"No."
"Nor am I either, Willis; but let me ask you how it is that the waves do not carry you along with them?"
"Because one wave neutralises the effect of another."
"Very good; but how is it that these ponderous waves, coming down upon you, do not crush you to atoms by their mere weight?"
"Well, I suppose that liquids do not operate in the same way as solids: perhaps there is something in our bodies that counterbalances the effect of the water."
"Very likely; and if such be the case as regards water, may it not be so also as regards air?"
"But I do not feel air; whereas, if I go into water, I not only feel it, but taste it sometimes, and I cannot force my way through it without considerable exertion."