tance offered by the air really is; and after making a dozen lusty strokes without appreciably advancing, he was ready to give up the undertaking in despair.
"Whew!" said he, panting, "if I can't get on any faster than this, with all my exertions, I sha'n't reach the floor in a year. Why, in swimming through water I M go ten times as fast! It seems to me that it ought to be just the contrary, and that, as air offers a much slighter resistance to my progress than water would, I ought to go faster here."
In speaking thus our hero did not take into account the fact that, although the resistance to his progress was much less, the force of impulse was correspondingly decreased. Consequently, since his advance was due to the difference between the propelling force and the resistance to his progress, the denser the medium in which he traveled, the quicker he would go, so long as the medium remained mobile. Hence he could swim through water very much faster than through air.
Another very peculiar fact which our hero noticed was that, in making these swimming motions, the speed of all his movements was
