One could stretch himself at full length on his back, with his arms on his breast, and all of his body above a line drawn from the corner of his jaw past the middle of his side, the middle of his leg and through his ancle bone, would remain out of water.

He could lift his head clear out, if he chose.

No position can be retained long; you lose your balance and whirl over, first on your back and then on your face, and so on.

You can lie comfortably, on your back, with your head out, and your legs out from your knees down, by steadying yourself with your hands.

You can sit, with your knees drawn up to your chin and your arms clasped around them, but you are bound to turn over presently, because you are top-heavy in that position.