The doctrine of the Earth’s rotundity being fallacious, all ideas of “centre of attraction of gravitation,” “mutual attraction of Earth and Moon,” &c., &c., must be given up; and the cause of tides in the ocean must be sought for in another direction. It is certain that there is a constant pressure of the atmosphere upon the surface of the Earth and ocean. This is proved by ordinary barometrical observations, many Pneumatic experiments, and by the fact that during the most fearful storms at sea the surface only is disturbed; at the depth of a hundred feet the water is always calm--except in the path of well-marked currents and local submarine phenomena. The following quotations gathered from casual reading fully corroborate this statement. “It is amazing how superficial is the most terrible tempest. Divers assure us that in the greatest storms calm water is found at the depth of 90 feet.”[21] [21] Chambers’s Journal, No. 100, p. 379. “This motion of the surface of the sea is not perceptible to a great depth. In the strongest gale it is supposed not to extend beyond 72 feet below the surface; and at the depth of 90 feet the sea is perfectly still.”[22] [22] Penny Cyclopædia, Article Sea. “The people are under a great mistake who believe that the substance of the water moves to any considerable depth in a storm at sea. It is only the form or shadow which hurries along like a spirit, or like a thought over the countenance of the ‘great deep,’ at the rate of some forty miles an hour. Even when the ‘Flying Dutchman’ is abroad the great mass of water continues undisturbed and nearly motionless a few feet below the surface.”[23] [23] London Saturday Journal, August 8, 1840, p. 71. “The unabraded appearance of the shells brought up from great depths, and the almost total absence of the mixture of any _detritus_ from the sea, or foreign matter, suggest most forcibly the idea of _perfect repose_ at the bottom of the deep sea.”[24] [24] Physical Geography of the Sea, by Lieut. Maury, p. 265. Bearing this fact in mind, that there exists a continual pressure of the atmosphere upon the Earth, and associating it with the fact that the Earth is a vast plane “stretched out upon the waters,” and it will be seen that it must of necessity slightly fluctuate, or slowly rise and fall in the water. As by the action of the atmosphere the Earth is slowly depressed, the water moves towards the receding shores and produces the flood tide; and when by the reaction of the resisting oceanic medium the Earth gradually ascends the waters recede, and the ebb tide is produced. This is the _general_ cause of tides. Whatever peculiarities are observable they may be traced to the reaction of channels, bays, headlands, and other local causes.