Page:The Works of John Locke - 1823 - vol 03.djvu/334



of the water that falls down from the clouds runs away upon the surface of the earth into channels, which convey it to the sea; and part of it is imbibed in the spungy shell of the earth, from whence sinking lower by degrees, it falls down into subterranean channels, and so under ground passes into the sea; or else, meeting with beds of rock or clay, it is hindered from sinking lower, and so breaks out in springs, which are most commonly in the sides or at the bottom of hilly ground.

Springs make little rivulets; those united make brooks; and those coming together make rivers, which empty themselves into the sea.

The sea is a great collection of waters in the deep valleys of the earth. If the earth were all plain, and had not those deep hollows, the earth would be all covered with water; because the water, being lighter than the earth, would be above the earth, as the air is above the water.

The most remarkable thing in the sea is that motion of the water called tides. It is a rising and falling of the water of the sea. The cause of this is the attraction of the moon, whereby the part of the water in the great ocean, which is nearest the moon, being most strongly attracted, is raised higher than the rest; and the part opposite to it on the contrary side, being least attracted, is also higher than the rest. And these two opposite rises of the surface of the water in the great ocean, following the motion of the moon from east to west, and striking against the large coasts of the continents that lie in its way, from thence rebounds back again, and so makes floods and ebbs in narrow seas, and rivers remote from the great ocean. Herein we also see the reason of the times of the tides, and why they so constantly follow the course of the moon.