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THE TIDE OF THE SEA AND THE TIDES OF THE AIR 187 his compeers, are sadly perplexed to find the curb that shall correct the destructive fury of the wave, which travels with the moon at the rate of 1,000 miles per hour into the harmless pulsation whose energies are wasted on a few feet of ocean strand. The moon theory of the tides originated with Aristotle. Pliny suggested an improvement on it in his "luni-solar theory." An attempt to improve upon this is found in the "Cotidal System," while this in turn is asserted by the "Derivative System" of Professor Norton, which conceives the moon to drag the wave (he uses the word drag) after it; but he too, like his predecessors, drags it the wrong way. Let us examine now some other points wherein the theory seems to be defective. Since it ascribes the tides to the potency of both moon and sun, allotting two-fifths of the resultant to the latter, it should be expected that when the sun and moon are in quadrature there should be four different tides at one and the same time on four different parts of the earth, at least during the maximum period of this phenomenon. The fact is otherwise, and the theorists explain the discrepancy by declaring the waters to obey the behests of the moon, fashioning themselves into a compound neap tide, and robbing the sun of his just claim to the two-fifths share in the achievement. At a quarter farther on the sun and moon are in opposition; they have the earth between them, and hence exert their attractive energy in opposite directions. We should therefore expect, upon reasonable analogy, to find as the resultant a feeble tide, for the attracting forces should partially neutralize each other, and we should have, instead of the flood-tide which really occurs, but a fractional part, one-fifth, of the combined attractive powers as a surplus for tidal effect. From these considerations we are, I hold, justified in seeking elsewhere for the explanation of the tides than in the theory which is plainly insufficient and, when carefully examined, glaringly inconsistent with itself. We may remark, in introducing the explanation we shall offer in its place, that there are other periodical phenomena, both in the living and lifeless kingdoms of Nature, which may as justly be claimed to be coincident with the phases of the moon as that of the tides, but in which to claim on that account relationship would be palpably absurd. They have their elucidation in, and are manifestly referable to, that harmonious pulsation of nature which exhibits itself in the throbbing of the heart, in the motion of the blood, the vibration of sound, the "nodding" of the poles of the earth, - in all mechanical movements, and in the measured cadence of the waterfall as it rises and falls in its musical rhythms. Herbert Spencer, in his chapter on the Rhythm of motion, says: "After having for some years supposed myself alone in the belief that all motion is rhythmical, I discovered that my friend Prof. Tyndall also held this doctrine." And here allow to state that in my earliest aërial voyages I noticed this nodding motion in nature manifested in various ways: in sounds, in the undulations of the balloon's course, but most expressively in the rotary motion of the aërial globe. In 1841, during an aërial voyage from the town of Danville, Pa., I noted the following in my log-book:* "During this voyage I observed a peculiar motion in the balloon, which had on former occasions drawn some attention from me, but which had not been closely investigated. It is this: When a balloon is sailing along with a steady current, while in equilibrium with the atmosphere, it revolves slowly on its vertical axis. This rotation is not at all times a smoothly continued circulation, but is pulsatory, like the notched wheel in a clock, as actuated by the pendulum. At first I attributed this motion to my breathing, believing the vibrations of the lungs sufficient to give a corresponding motion to so delicately balanced a thing as a balloon is when suspended in space. I held my breath as long as I could, and this was done several times, but the pulsations of the balloon were not interrupted by it; on the other hand, they became more audible during these experiments. Upon timing these pulsations I found them to be every two and a half seconds, and very regular. This left me at a loss to account for this motion, as it seemed not to be caused by my breathing, and did not correspond to the beat of my pulse." I noticed this peculiarity of the balloon's motion always when it was sailing along horizontally at great altitudes where it seemed to be uninfluenced by the irregularities of the earth's surface. The ocean tides express this rhythmical pulsation as they beat the shores of the continent, in their breathing and heaving motions, keeping time as it were with nature's balance-wheel, universal gravitation. We see it's evidences in the eruptions of volcanoes, in the earthquakes, in the great storms and * History and Practice of Aëronautics, page 212.
