Perfectly to comprehend this we must attend to the nature of the power which produces the tides. We have observed that the moon acts upon the earth by a power called attraction by some, and by others gravity: this force penetrates through the globe, is exactly proportioned to the quantity of matter, and decreases as the square of the distance increases. Let us next examine what must happen to the waters when the moon is at the meridian of any one place.--The surface of the waters being immediately under the moon is then nearer that planet than any other part of the globe; hence this part of the sea must be elevated towards the moon, by forming an eminence, the summit of which must be opposite to the moon's centre; for the formation of this eminence the waters at the bottom, as well as at the surface, contribute their share, in proportion to the proximity they are in of the moon, which acts upon them in the inverse ratio of the squares of their distances: thus the surface of that part of the sea is first raised; the surface of the neighbouring parts will be likewise elevated, but to a less height, and the water at the bottom of all these parts will be raised by the same cause; so that all this part of the sea growing higher and forming an eminence, it is necessary that the water of the remote parts, and on which this force of attraction does not act, proceeds with precipitation to replace the waters which are thus elevated and drawn towards the moon. This is what produces the flux, or high tide, which is more or less sensible on different coasts, and which agitates the sea not only at its surface but even to the greatest depths. The reflux, or ebb, happens afterwards by the natural inclination of the water, for when the moon no longer uses its power, the water which was raised by this foreign power retakes its level, and returns to the shores and places it had been forced to quit. When the moon passes to the antipode, or opposite meridian, the same effect ensues, though from a different cause, In the first case the waters rise because they are nearer the planet than any other parts of the globe; and in the second it is from the contrary reason, they rise because she is the most remote from them; and this it is easily perceived must produce the same effect, for the waters of this part being less attracted than those of the opposite hemisphere, they will naturally recede and form an eminence, the summit of which will answer to the point of the least action that is directly opposite to the moon's station, or where she was thirteen hours before. When the moon arrives at the horizon the tide is ebb, the sea is then in its natural state, and the water in a direct equilibrium; but when she is at the opposite meridian this equilibrium can no longer exist, since the waters of the part opposite to the moon being at the greatest distance possible from her, they are less attracted than the remaining part of the