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During new and full moon, the earth, moon, and sun are all in the same straight line, but, that during the first and last quarters, they are at right angles. The portions of the earth and moon turned toward the sun are illumined, the shaded portions are in the darkness. To an observer on the earth, the moon, at <em>a</em>, appears new, since the dark part is turned toward the person; at <em>b</em>, however, it must appear full, since the illumined portions are toward the person. At <em>c</em>, and <em>d</em>, the positions of the quarters, only one-half of the illumined half, or one quarter, is seen.

Cause of the Phases of the Moon

During new and full moon, the earth, moon, and sun are all in the same straight line, but, that during…

If the earth were uniformly covered with a layer of water, the passage of the moon over any place as at <em>a</em>, would cause the water to lose its globular form, become bulged at <em>a</em>, and <em>b</em>, and flattened at <em>c</em>, and <em>d</em>. In other words, the water would become <em>deeper</em> at <em>a</em>, and <em>b</em>, at the parts of the earth nearest and farthest from the moon and <em>shallower</em> in all places 90 degrees or at right angles to these points.

Lunar Tide

If the earth were uniformly covered with a layer of water, the passage of the moon over any place as…

The flood tides are the highest, and the ebb tides are the lowest. These are called <em>spring tides</em>. They occur twice during every revolution of the moon-once at <em>full</em>, and once at <em>new</em> moon. When the sun and moon are 90 degrees apart, each produces a tide on the portion of the earth directly under it, diminishing somewhat produced by the other body. High tide, then, occurs under the moon, while the high tide caused by the sun, becomes by comparison, a low tide. Such tides are called <em>neap tides</em>.

Positions

The flood tides are the highest, and the ebb tides are the lowest. These are called spring tides.…