In order to facilitate our reasoning I have assumed that the moon is the only tide-producing agent; this is, however, not the case. No doubt the ebb and the flow around our coasts is generated mainly by the attraction of the moon. It must not, however, be forgotten that a portion of the tide is originated by the attraction of the sun. These solar tides will still continue to ebb and flow quite independently of the lunar tides, so that even if the accommodation between the earth and the moon had been completed some further tidal disturbance would not be wanting. The effect of the solar tides will be to abate still further the velocity with which the earth turns round on its axis, and consequently a time must ultimately arrive when the length of the day will be longer than the time which the moon takes to revolve around our earth. THE GULF STREAM --LORD KELVIN I mean by the Gulf Stream that mass of heated water which pours from the Strait of Florida across the North Atlantic, and likewise a wider but less definite warm current, evidently forming part of the same great movement of water, which curves northward to the eastward of the West Indian Islands. I am myself inclined, without hesitation, to regard this stream as simply the reflux of the equatorial current, added to no doubt during its northeasterly course by the surface-drift of the anti-trades which follows in the main the same direction. The scope and limit of the Gulf Stream will be better understood if we inquire in the first place into its origin and cause. As is well known--in two bands, one to the north and the other to the south of the equator--the northeast and southeast trade-winds, reduced to meridional directions by the eastward frictional impulse of the earth’s rotation, drive before them a magnificent surface current of hot water 4,000 miles long by 450 miles broad at an average rate of thirty miles a day. Off the coast of Africa, near its starting-point to the south of the Islands of St. Thomas and Anna Bon this “equatorial current” has a speed of forty miles in the twenty-four hours, and a temperature of 23° C.