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[[margin note]] Read before the Franklin Institute in 1871 and printed in Scribner's Monthly of June 1873, by J. W. [[margin note]] 186 THE TIDES OF THE SEA AND THE TIDES OF THE AIR. THE TIDES OF THE SEA AND THE TIDES OF THE AIR. Giordano Bruno expiated at the stake the crime of teaching the motion of the planets differently from the Ecclesiastical authorities of his time, and Galileo, at a later period, only avoided a similar fate at the expense of an imbittered life and a blasted reputation; but in this age of intellectual progress the most humble searcher of truth may venture to differ from "authority," though it passes wide-spread recognition and acceptance - and may even promulgate what he deems to be a more correct interpretation of facts, fearing no severer punishment than the incredulity of those who have imbibed ancient notions, wrong though they may be. With this introduction, which owes its presence to strong consciousness of the temerity of the following views, let me invoke a candid judgement and attention to the consideration of the phenomena of the Tides. It is a problem with equals, if it does not surpass in difficulty, any of those to which the student of nature finds himself opposed, and if I may not hope that the views I shall have present will carry conviction with them, I have strong faith that I shall leave my readers at least impressed with the knowledge of the insufficiency of the widely accepted theory, which now claims to solve it, as written in the books. To enter at once upon the subject: The current theory to which we have referred presupposes a condition of earth and water which has no existence in fact. It presupposes that the earth is entirely covered with water. This being assumed, it is argued that the attractive power of the moon, at times aided by the sun, will and does draw up a protuberance of water upon the side of the earth turned towards them. When in conjunction, three-fifths of this lifting power, aptly termed the pull of gravitation, is ascribed to the moon, and the remaining two-fifths to the sun. The reasoning here employed necessitates the coincidence of high water, i.e., high tide with the meridian position of the moon; but the fact is, such coincidence has never been observed. The ordinary tides vary as much as three hours from the time demanded upon the theory; while under circumstances which should triumphantly sustain it, - I refer to the conjunction of the sun and moon, - the flood tide differs by some 36 hours from the time at which it should occur. It is one of Professor Huxley's profoundly philosophical utterances, that "A scientific definity of which an unwarrantable hypothesis forms an essential part carries its condemnation within itself." With such sound doctrine to guide us, we may safely criticise the theory of the tides. That the earth is entirely covered with water is, I think none of my readers will deny, an unwarrantable hypothesis, - for it is totally inconsistent with fact, - and I am of the opinion that it drags the theory of which it forms an essential conception into the category of those "which carry their condemnation within themselves." I think we will be able to detect other discrepancies than this if we subject the theory to be searching examination. The differences between the theoretical and actual times of the occurrence of high water have already been mentioned as one of them; but, contenting ourselves at present with the mere mention of if, we will find the theory numbered with another conception equally incompatible with truth; namely, that the tidal wave travels with the moon about the earth from east to west once in about 25 hours. Now it can be shown in fact, and is continually recognized in the practice of mariners, that the tidal wave travels about the earth in precisely the opposite direction - from west to east. That this is the real condition of things I shall shortly, I hope, abundantly convince you, and for its cause I would assign a new factor, heretofore entirely overlooked in the elucidation of tide phenomena, to wit, that of centrifugal force, springing from the law of gravitation, a force that whirls the water forward in mid-ocean, as the water is thrown forward on a revolving grindstone. Guillemin, in his treatise on astronomy, after an exhaustive chapter on the tides in which the "inequality of attraction" and the action of "distant molecules" are lucidly mystified, concludes, as it were in despair of a reasonable explanation, with the following statement. "In a word, on one side the water is pulled from the earth, on the other the earth is pulled from the water." To Guillemin too must belong the credit of the announcement that "natural laws suffice to put a curb upon the fury of the waves," though as to the precise nature of these laws he leaves his reader to conjecture; and it is no wonder, seeing that not only he, but all
