Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER III. THE SEA. Lesson XII.—The Great Sea-basins. 1. From the outer envelope of air which encloses the earth we now pass to the underlying envelope of water called the Sea. At the outset some obvious differences between these two coverings may be noticed. For example, while the atmosphere completely wraps round the whole planet, rising to a height of many miles above its general surface, the water envelope is pierced in many places by masses of the underlying solid part of the earth, which rise above it to form land. As the result of observations in all parts of the world it has been ascertained that the sea covers not quite three quarters, and the land a little more than one quarter, of the entire surface of the earth ; or more accurately, the sea spreads over 144,712,000 square miles, and the land over 52,000,000 square miles, the total area of the surface of the globe being computed at 196,712,000 square miles. 2. Again, we know nothing about the upper surface of the atmosphere, and cannot say precisely how far it lies above us, but the surface of the sea forms a great plain, and the line between it and the air is sharply defined. Though we speak of the sea as forming a plain, we knowthis plain to be really curved, and that Irom its wide extent and its freedom from inequalities, it shows the curvature of the earth's surface better than can be seen on land. (Lesson I. 2.) The amount of the curvature is about eight inches in a statute mile ; that is, an object eight inches high above the sea-level sinks out of sight when looked at from the same level at a distance of more than a mile. The line of meeting between the sky and the surface of the earth is termed the horizon. Its distance from us evidently depends upon the elevation at which we may happen to stand. Thu...