Q. Why is stagnant water full of worms, eels, &c.?
A. Because numberless insects lay their eggs in the leaves and plants which float on the surface; these eggs are soon hatched, and produce swarms of worms, eels, and insects.
Q. Why are flowing waters free from these impurities?
A. 1st—Because the motion of running water prevents its fermentation:
2ndly—It dissolves the putrid substances which happen to fall into it: and
3rdly—It casts on the bank (by its current) such substances as it cannot dissolve.
Q. Why does running water oscillate and whirl in its current?
A. 1st—Because it impinges against its banks, and is perpetually diverted from its forward motion: and
2ndly—Because the centre of a river flows faster than its sides.
Q. Why do the sides of a river flow more tardily than its centre?