cipations penetrate more profoundly into nature than he would be capable of doing by the most extensive course of reading, by indefinite abstract speculations, or by continual and repeated disputations; though he may not have brought the ordinary engines into action, or have adopted the prescribed formula of interpretation.

ourselves peremptorily bound by what we are about to bring forward, of whatever character it may be, to the maintenance of the whole of our secondary and inductive philosophy. This result of our meditations we have determined to offer loosely, and unconfined by the circumscription of method; deeming this a form both better adapted In this, however, we do not wish to be con- to sciences newly springing up as from an old sidered as demanding for our own dogma the au- stock, and more suitable to a writer whose prethority which we have withheld from those of sent object it is not to constitute an art from comthe ancients. We would rather, indeed, testify | bined, but to institute a free investigation of indiand proclaim, that we are far from wishing to be ❘vidual existences.

F. W.

MISCELLANEOUS TRACTS.

[TRANSLATED FROM THE LATIN.]

OF THE EBB AND FLOW OF THE SEA.

THE investigation of the causes of the ebb and | which return at regular periods of the year. That flow of the sea, attempted by the ancients and in consequence of these and similar causes, they then neglected, resumed by the moderns, but vary their states of flow and eddy, both as relates rather frittered away than vigorously agitated in to extending and widening the motion itself, and a variety of opinions, is generally, with a hasty to the velocity and measure of the motion; and anticipation, directed to the moon, because of thus produce what we term currents. Thus, in certain correspondences between that motion, and the seas the depth of the basin or channel, the the motion of that orb. But to a careful inquirer occurrence of whirlpools or submarine rocks, the certain traces of the truth are apparent, which curvature of the shore, gulfs, bays, the various may lead to surer conclusions. Wherefore, to position of islands, and the like, have great effect, proceed without confusion, we must first distin-acting powerfully on the waters, their paths, and guish the motions of the sea, which, though agitations in all possible directions, eastward and thoughtlessly enough multiplied by some, are in westward, and in like manner northward and reality found to be only five; of these one alone southward; wherever, in fact, such obstacles, is eccentric, the rest regular. We may mention | open spaces, and declivities exist in their respect first the wandering and various motions of what|ive formations. Let us then set aside this parare called currents: the second is the great sixhours motion of the sea, by which the waters alternately advance to the shore, and retire twice a day, not with exact precision, but with a variation, constituting monthly periods. The third is the monthly motion itself, which is nothing but a cycle of the diurnal motion periodically recurring: the fourth is the half-monthly motion, formed by the increase of the tides at new and full moon, more than at half-moon: the fifth is the motion, once in six months, by which, at the equinoxes, the tides are increased in a more marked and signal manner.

It is the second, the great six-hours or diurnal motion, which we propose for the present as the principal subject and aim of our discourse, treating of the others only incidentally and so far as they contribute to the explanation of that motion.

First, then, as relates to the motion of currents, there is no doubt that to form it the waters are either confined by narrow passages, or liberated by open spaces, or hasten as with relaxed rein, down declivities, or rush against and ascend elevations, or glide along a smooth, level bottom, or are ruffled by furrows and irregularities in the channel, or fall into other currents, or mix with them and become subject to the same influences, or are affected by the annual or trade winds,

ticular, and, so to speak, casual motion of the
waters, lest it should introduce confusion in the
inquisition which we now pursue.
For no one
can raise and support a denial of the statement
which we are presently to make, concerning the
natural and catholic motions of the seas, by
opposing to it this motion of the currents, as not
at all consistent with our positions. For the cur-
rents are mere compressions of the water, or
extrications of it from compression: and are, as
as we have said, partial, and relative to the local
form of the land or water, or the action of the
winds. And what we have said is the more
necessary to be recollected and carefully noted,
because that universal movement of the ocean of
which we now treat is so gentle and slight, as to
be entirely overcome by the impulse of the cur-
rents, to fall into their order, and to give way, be
agitated, and mastered by their violence. That
this is the case is manifest particularly from this
fact, that the motion of ebb and flow, simply, is
not perceptible in midsea, especially in seas
broad and vast, but only at the shores. It is,
therefore, not at all surprising, that, as inferior
in force, it disappears, and is as it were annihi
lated amidst the currents; except that where the
currents are favourable, it lends them some aid
and impetuosity, and, on the contrary, where they

quantity of water added, it must be by flowing and eruption from the earth. If there were dilatation only, this must take place either by solution into greater rarity, or by a tendency to approach another body, which, as it were, evokes the waters, attracts them, and lifts them to greater elevation. And, doubtless, that state of the waters, whether considered as ebullition, or rare

are adverse considerably restrains them. Waiving and supply its place. If there were a fresh then the motion of the currents, we proceed to the four regular motions; that in the six hours, in the month, in the half month, and in six months, of which the sexhorary motion alone seems to produce and develope the ordinary tide, the monthly to determine that motion and define its renewal; the half-monthly and half-yearly to increase and strengthen it. For the ebb and flow, which cover and quit again a certain extent of shore, both vary | faction, or harmony with some one or other of the at various hours, and according to the momentum heavenly bodies, cannot seem incredible, that is, and quantity of the water; whence these three to a moderate extent, and on the supposition of the other motions are rendered more perceptible. lapse of considerable time, in which such swellWe must, therefore, contemplate, singly and ings and accretions may gather and accumulate. specifically, as we purposed, the motion of ebb Therefore the difference observable between the and flow. And, first, it is necessary to grant that ordinary, and the half-monthly tide, or the most this motion, the subject of inquiry, is one of these copious of all, the half-yearly one, in which the two: either the motion of an elevation and depres‐addition to the mass of waters is not equal to sion, or the motion of a progression of the waters. The motion of elevation and depression we understand to be such, as is found in boiling water, mounting and subsiding alternately in a caldron : the motion of progression to be such as is observed in water carried in a basin, which quitting the one side, is projected to the opposite. Now, that the motion we treat of is not of the former sort, is in the first place suggested by this fact, that in different parts of the world the tides vary according to the times, so that in certain places there are floods and accumulations of the mass of waters, in others at the same hours ebb and diminutions. Now, the waters, if they did not travel from place to place, but rose ebullient from the bottom, ought to rise everywhere at once, and to subside together. For we see those two other motions, the monthly and half monthly, in full movement and operation at the same periods throughout the globe. For the waves increase at the equinoxes in all parts, not in certain places under the equator, or in others under the tropics: and the same is true of the half-monthly motion. For, everywhere over the world, the waters are elevated at new moon and full moon, nowhere at half-moon. The waters, therefore, are manifestly raised, and again depressed in these two motions, and like the heavenly bodies have their apogees | to be the case if the entire mass of waters had a and perigees. But in the ebb and flow of the sea, which we now discuss, the contrary takes place, an unequivocal sign of progressive motion. Besides, ere we set down the flow of the sea as an elevation of the waters, we ought to consider a little more carefully how that elevation can take place For the swelling must either be produced by an augmentation of the mass of waters, or from an extension or rarefaction of fluid in that mass, or from simple elevation of the mass or body. The third supposition we must dismiss entirely. For if the water united in the same body were lifted up, a vacuum would necessarily be left between the earth and the under face of the water, there being no body ready to succeed

the difference between ordinary ebb and flow, and has besides a large interval of time insensibly to form, may, on the hypothesis of elevation and depression, be consistently explained. But that so great a mass of water should burst forth as to explain that difference which is found between the ebb and flow, and that this should take place with such extreme rapidity, namely, twice a day, as if the earth, according to the fantastic notion of Apollonius, performed respiration, and breathed waters every six hours, and then again inhaled them, is very hard to believe. And let no man be misled by the unimportant fact that in some places wells are said to have a simultaneous motion with the ebb and flow of the sea, whence one might conjecture, that waters enclosed in the entrails of the earth boil up in like manner, in which case that swelling of the waters cannot be attributed to a progressive motion. For the answer is an easy one, that the flow of the sea by its encroachment may perforate and gorge many hollow and loose places of the earth, turn the course of subterraneous waters, or cause a reverberation of the enclosed air, which by a continued series of impulsions may raise the water in this sort of wells. Accordingly, this does not take place in all wells, nor even in many, which ought

property of periodically boiling up, and a harmony with the tide. But, on the contrary, this rarely happens, so as to be regarded almost as a miracle, because, in fact, such apertures and spiracles as reach from wells to the sea, without circuity or impediment, are very rarely found; nor is it unimportant to mention, what some relate, that in deep pits situated not far from the sea, the air becomes thick and suffocating at the time of ebb, from which it may seem manifest, not that the waters boil up, (for none are seen to do so,) but that the air is reverberated. No doubt, there is another objection, not despicabie, but of great weight, every way deserving of an answer, one which had been the subject of careful observation,

and that not incidentally, but a thing especially | bodies. Notwithstanding, it will not immedi and of purpose inquired into and discovered, ately follow from this, and we would have men namely, that the water at the opposite shores of note the observation, that those things which Europe and of Florida ebb at the same hours agree in their periods and curriculum of time, or from both shores, and do not quit the shore of even in their mode of relation, are of a nature Europe when they roll to the shore of Florida, subjected the one to the other, and stand respectlike water (as we have said before) agitated in a ively as cause and effect. Thus we do not go so basin, but are manifestly raised and depressed at far as to affirm, that the motions of the sun ought either shore at once. But a clear solution of this to be set down as the causes of the inferior moobjection will be seen in the observations which tions which are analogous to them; or that the shall presently be made about the path and pro- sun and moon (as is commonly said) have domigression of the ocean; the substance, however, nion over these motions of the sea, although such is this; that the waters, setting out in their course notions are easily insinuated into our minds from from the Indian ocean, and obstructed by the veneration of the heavenly bodies; but in that remora of the continents of the old and new very half-monthly motion, if it be rightly noted, world, are impelled along the Atlantic from south it were a new and surprising kind of subjection to north; so that it is no wonder if they are driven to influence, that the tides at new and at full against either shore equally at the same time, as moon should be affected in the same manner, waters are wont to be, which are propelled from when the moon is affected in contrary ways; and the sea into estuaries and up the channels of many other things might be instanced, destroying rivers, evidently showing that the motion of the similar fancies of this sort of dominant influence, sea is progressive as respects the rivers, and yet and leading to this inference, that those corresthat it at once inundates both shores. Notwith- pondences arise from the catholic affections of standing, according to our custom we freely con- matter, from the primary concatenation of causes, fess, and would have men observe and remember, and connexion of things; not as if such were that if it is found in experience that the tide ad- governed the one by the other, but both flowed vances at the same time on the coast of China from the same sources and from joint causes. and Peru, as on that of Europe and Florida, this Notwithstanding this, however, it remains true, our opinion, that ebb and flow is a progressive as we have said, that nature delights in harmony, motion of the sea, must be repudiated. and scarcely admits of any thing isolated or solitary. We must therefore look, in treating of the sexhorary ebb and flow of the sea, with what other motions it is found to agree and harmonize. And first we must inquire with respect to the moon, in what manner that motion blends relations or natures with the moon. not see prevail except in the monthly repairing of the moon, for the periodical course of six hours has no affinity with the monthly course; nor again are the tides found to follow any affections of the moon. For, whether the moon be crescent or waning, whether she be under the earth or above the earth, whether her elevation above the horizon be higher or lower, whether her position be in the zenith or elsewhere, in none of these relations do the ebb and flow of the tide correspond with her.

For if the flow of the sea takes place at the same time at the opposite shores, as well of the Pacific or Southern Ocean as of the Atlantic | Ocean, there are not in the universe any shores remaining, at which a corresponding ebb, at the same time, might afford a satisfactory solution of the objection. But we propose with confidence of a trial of this by experiment, to whose test we submit our cause: for we are clearly of opinion, that were the general result of a trial of this fact through the world known to us, this compact of nature would be found effected on sufficiently reciprocal conditions, namely, that at any given hour as much reflux took place in some parts of the world as flow in others. Therefore, from what we have stated, this motion of ebb and flow may be affirmed progressive.

But this we do

Therefore, leaving the moon, let us inquire Now follows the inquiry, from what cause and concerning other correspondences; and from all what combination of things this motion of ebb the motions of the heavenly bodies, it is certain and flow arises and is presented to view. For all that the diurnal motion is the shortest, and is the great movements (if these be regular and per- accomplished in the least period of time, that is, petual) are not isolated, or (to use here an expres- in the space of twenty-four hours. It is therefore sion of the astronomers) ferine, but have some- in harmony with this, that the motion of which thing in nature with which they move harmoni- we inquire, which is yet three times shorter than ously. Therefore those motions, as well as the the diurnal one, should be referred immediately half-monthly one of increase as the monthly of to that motion which is the shortest of the reparation, appear to accord with the motion of the heavenly ones. But this notion has no great moon; and again the half-monthly, or equinoctial, weight with us in this matter. Another hypo with the motion of the sun; also the elevations thesis has more influence with us, that this motion and depressions of the water, with the approxi- is so distributed, that, though the motion of the mation and revolution in the orbits of the heavenly waters is slower by innumerable degrees, still it

is referable to a common measure. For the space | and with the same conversion: but in the tropics of six hours is a quarter of the diurnal motion, they are not generally so confined, nor move in which space (as we said) is found in that motion of the sea, with a difference coinciding with the measure of the moon's motion. Whereupon this belief sinks deep into our mind, and looks as it were an oracular truth, that this motion is of the same kind with the diurnal motion. With this, therefore, as a basis, we shall proceed to a thorough inquiry: and we think that the whole subject is exhausted in three points of investigation.

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