Chemical and Physical Papers. 59 



produces the tidal phenomenon of the eastern coasts. On the other 

 hand, the accelerated eastern flow, striking the normally moving 

 west coast lands, rushes over them and drowns them in its billows. 

 Thus we have on one side the land plowing into the sea, and on the 

 other the sea overwhelming the land. 



Now, let us investigate the situation on the prolunar geohemi- 

 sphere. Directly under the moon and exactly opposite the high 

 point is the lowest spot on the face of the hydrosphere, which cov- 

 ers nearly three-fourths of the spherical area. It is the lowest be- 

 cause it is the one nearest the geolunar gravity center. It is the 

 one spot toward which all the waters of the hemisphere are flowing 

 in seeking their level. The waters to the west of it, flowing east- 

 ward, are the accelerated waters ; those to the east, flowing west- 

 ward, are the retarded waters; but they sustain the same relations 

 to the coast-lines as on the other hemisphere. If we now connect 

 the two hemispheres and trace the tidal sweeps from one to the 

 other we find continuous flows from the high point to the low point, 

 starting in opposite ways. The waters of the ocean are seeking 

 their level precisely as the rivers do; as, for instance, the Sacra- 

 mento and the San Joaquin, of California, from the northwest and 

 southeast, respectively, find their level in the bay of San Francisco. 



It is well known that water does not move as a solid body does — 

 at the same rate of motion throughout its mass — but some parts 

 move swifter than others, the free surface having lesser friction to 

 overcome, and the deeper and denser, the greater, give to the visible 

 current a rolling appearance ; hence we habitually and correctly 

 speak of the rolling wave, the rolling river, as "the flow of Isar 

 rolling rapidly." In the tidal wave there is always a thin, wedge- 

 shaped advanced stratum in front of the main mass, and a like 

 stratum lagging at the origin of the flow. We may call the high and 

 the low points described above the tidal poles. It is at these poles 

 that the moving floods are most shallowed, and midway between 

 that they are most thickened. When the poles pass the coasts, or, 

 rather, when the coasts pass the poles, at the velocity of about 14| 

 degrees an hour, it is the extreme of ebb, and when they pass the 

 midway points it is the acme of flood. 



We may now consider the direct influence of the moon upon the 

 earth's surface, without regard to the geolunar gravity center. If 

 the moon's center were within 4000 miles of the earth's surface, the 

 influence of the satellite upon the hydrosphere would be in the 

 ratio of its mass to that of the earth's, and a pound normal of 7000 

 grains would be diminished in weight about 87 to 88 grains on 



