BUREAU OF LAISSEZ FAIRE |
| DIRECTOR Macarius Zhi |
ABOUT
Men cannot swim naturally, though they are specifically lighter than water. For their heads are very large, and require to be almost all out of the water for breathing. And their way of Unking has no relation to that of walking. Men attain the art of fwimming by practice and induftry. And this art confifts in ftriking alternately with the hands and feet in the water, which lik,e oars will row him forward. When he ftrikes with his hands, he neither keeps the palms parallel nor perpendicular to the horizon, but inclined. And his hands ftriking the water obliquely, the refiftance of the water moves him partly upward, and partly forward. Whilft his hands are ftriking, he gradually draws up his feet; and when the ftroke of his arms is over, he ftrikes with his feet, by extending his legs, and thrufting the foles of his feet full againft the water. And while he ftrikes with his legs, he brings about his arms for a new ftroke, and fo on alternately. He muft keep his body a little oblique, that he may more eafily erect his head, and keep his mouth above water.
After the feme manner may the motions, velocities, powers, and properties of any machine be explained and accounted for, by mechanical principles. I mall proceed to lay down a fhorc defcription of feveral other machines, without being fo particular in the calculation of their powers and forces. The mechanifm of which being underftood, will affifl the invention of the practical mechanic, in contriving a machine for any ufe.