"Thank you for the comparison--not for the first time, Master Tyd--but I have not a great belly like a frog's, which is useful in swimming--at least in floating. A large pot-bellied man may lie on the water as long as he likes, if he keeps his head well back so as to have it supported by the water--and with his heels closed and neck up." "But surely in that position he would be like a log on the water, and make no way," remarked some one of the listeners. "True, but he can rest himself in that position until he chooses to strike out again. Just fancy yourself a fish: you are specifically lighter than water, and you can lie as near the surface as you please; use your fins and you can move about to the right or left--as a boat is moved by its oars; use your tail and you steer in any direction--as the rudder turns the direction of the boat. Then fancy your fins and tail cut off--there you lie like a raft--without poles or oars--but you do not sink. If you have one fin, or part of one, you move like a boat with one whole or broken oar. Now our bodily apparatus is not designed like that of a fish for swimming, but it is capable of enabling us to swim sufficiently well for our necessities. Just read Old Franklin on the art of swimming, and you will understand the theory of the matter at once. The great difficulty in practice is the fear which people have of being drowned, and this can only be overcome by accustoming ourselves to the water." "Now, Mack," said Tydvill, "you know I cannot swim; what ought I to have done if you had pitched me into that awful hole?" "You should have kept yourself from struggling and plunging, letting the back of your head lie quietly under the water, with your mouth free for breathing--but not for screaming and water-drinking--till I had taken the trouble of catching hold of you." "But surely," replied Tydvill, "the weight of my clothes would have sunk me?" "I think not," rejoined his friend; "the water would have supported them too, though you'd have found them very heavy when you came out of it. Will you try the experiment?" "The theory is sufficient for me," concluded the sprightly Welshman. However, another of the crew put this question:-- "Since the body can be supported on the surface of the water, as O'Mackerry has said, and with little exertion, or without any, as in swimming on the back, how is it that a drowned body sinks, and often rises some days afterwards?" "Because," said our philosopher,--who had been crammed on the subject,--"the lungs of a drowning person become filled with water, and therefore the body, becoming specifically heavier, sinks. The body remains at the bottom only until the water has been quite freed from it by _compression_; it then is swelled and expanded by gases generated within, and becoming lighter than the water, rises to the top."