Every one is familiar with the effects of rain. A heavy fall upon the tops of the mountains detaches the various sized particles already loosened by the action of the atmosphere. They are hurried along by the little rills into the brooks, by the brooks into the rivers, and finally by the rivers into the sea, the waters of which are partially tinged with these turbid streams. Every river, in the whole earth, is more or less heavily charged with earthy matter, on its reaching the parent ocean. The nature and colour of this muddy mixture must depend upon those of the countries through which the rivers flow.

Having now traced the course of this earthy matter to the sea, it becomes necessary to observe in what way it is disposed of, in the bosom of the depths; and, for this purpose, we must consider the nature and action of this great body of waters. The continual influence of the moon, aided in a less powerful degree by the attraction also of the sun, is known to be the occasion of the tides which assist in keeping up the circulation of the waters.* But a much more power

standing thick upon the surface, and, in the end, running down in copious streams, like a violent perspiration. The common objection made to such stones, is, that they retain moisture, and perspire at certain times; this, however, is a vulgår error.

If a house be built upon a clay soil, the dampness, which is a usual consequence, does not arise so much from the clay being wet in itself,' as from its great coldness, which condenses the warm air of the atmosphere, and thus forms a constant moisture. It is obvious, then, that sand stone, or brick, as a material, and a light sandy soil, as a foundation, must produce the most dry and healthy dwelling.

*The following clear description of the tides is given by Sir Da vid Brewster, in his "Life of Sir Isaac Newton."

"One of the great subjects to which Newton applied the principles of attraction and gravity, was, the tides of the ocean. Philosophers of all ages had recognized the connection between the phenomena of the tides, and the position of the moon. That the moon is the principle cause of the tides is obvious, from the well known fact, that it is high water at any given place about the time when she is in the meridian of that place; and that the sun performs a secondary part in their production, is proved by the circumstance, that the highest, or spring tides, take place when the sun, the moon, and the earth, are all in a straight line; that is, when the force of the attraction of the sun conspires with that of the moon; and that the lowest, or neap tides, take place when lines drawn from the sun and moon to the earth, are at right angles to each other; that is, when the force of the attraction of the sun acts in opposition to that of the moon. But the most perplexing phenomenon in the tides, and one which is still a

ful agent is continually at work in producing this effect; and as this agent, and its effects, do not come so familiarly within our view, its power is not so generally understood or acknowledged. This agent is the general system of the currents in the ocean.

These currents have long been remarked by voyagers in every part of the sea; and they have been found so powerful that vessels are constantly borne out of their course, unless due allowance be made for their influence. It was long supposed that these rivers in the ocean were occasioned by the action of the tides: but modern science and observation has proved this idea to have been unfounded; and has discovered that there is as regular a circulation in the great deep as in the veins of the human body. These currents chiefly arise from the following causes. In consequence of the powerful action of the sun in tropical climates, the loss by evaporation from the sea, is much greater than can be supplied by the quantity of rain which falls in these latitudes. The moisture thus imbibed by the atmosphere, passes into the regulár circulation of the air; and when carried into the temperate or polar regions of the earth, it becomes condensed, and falls there in much greater quantity than these regions lose by evaporation. This superabundant supply of water cannot, from the figure and motion of the earth, remain where it falls, but rushes back towards the equator in currents, the directions of which must depend, in a great measure, on the stumbling-block to persons slightly acquainted with the theory of attraction, is the existence of high water on the side furthest from the moon, at the same time as on the side next the moon. To maintain that the attraction of the moon at the same time draws the waters of the earth towards herself, and also draws them from the earth in an opposite direction, seems, at first sight, paradoxical. But the difficulty vanishes, when we consider the earth, (or rather the centre of the earth,) and the waters on each side of it, as three distinct bodies, placed at different distances from the moon, and, consequently, attracted with forces inversely proportioned to the squares of their distances. The waters nearest the moon will be much more powerfully attracted than the centre of the earth, and the centre of the earth more than the waters furthest from the moon. The consequence of this must be, that the waters nearest the moon will be drawn away from the centre of the earth, and will, consequently, rise from their level; while the earth will be drawn away from the waters opposite the moon, which will, as it were, be left behind, and be in the same situation as if raised from the earth in a direction opposite to that in which they are attracted by the moon."

forms of the coasts they may meet with in their course: and as no strong current can take place either in the air or in the waters, without a variety of eddies, or counter currents, as we familiarly know, on a small scale, by observing a strong stream in any river, or by the draughts of air in our houses, such are abundantly to be found in the ocean, and sometimes on so large a scale, and in such a direction, as might appear in opposition to the system above explained, unless the whole be viewed upon an enlarged scale. It has been supposed by some, that the winds, and especially the regular trade winds, have a great influence on the currents of the ocean, and may even be regarded as the cause of this constant motion in the waters. But this is taking too superficial a view of the subject. It is known that the currents of the air affect the surface of the waters, merely by contact and friction in the same manner as in the friction of any other two substances; and however the surface of the ocean may be agitated by this contact, and raised into waves by its force, we cannot suppose it capable of acting to any considerable depth, or of displacing large bodies of water. It is, indeed, understood, that though the swell of a wave advances on the surface, the water over which it moves remains nearly stationary; so that, although the winds may, in some small degree, aid or impede the tides or the currents, they cannot be considered the cause of the movement, any more in the one case than in the other. There appears to be a close resemblance between this circulation kept up in the waters, and that known to exist in the atmosphere. In the latter we have winds of various power and continuance, and also whirlwinds, occasioned, like the whirlpools in fluids, by the action of two contrary streams, or by the disturbance occasioned by an opposing object. There are also such decided counter-currents in the air, from the effort to preserve a just balance in that element, that it is a common practice with aeronauts to send up a small balloon before launching their larger one, in order to discover in what direction the upper currents of the wind may be setting.

The whole system of the currents in the ocean can probably never be distinctly defined, on account of its great extent, and the very partial observations of voyagers. Besides, there must be a constant though slow alteration in the directions of their smaller divisions, according as the opposing objects are gradually worn away. But the general outline of the larger branches may be traced with tolerable distinctness,

and may be here explained as they now exist in our own times. The present great system of currents, then, may be traced from the western coast of America across the Pacific ocean; of this current we as yet know little, but that it exists. But one branch of it strikes on the south of New Holland, running through Bass's Straits, round South Cape; and another branch runs amongst the islands of the Archipelago, on the north of New Holland. On entering the Indian ocean, and meeting the south polar current, it runs through the gulf of Bengal, round cape Comorin, and over to Africa, acquiring great velocity in its passage. From the straits of Babelmandel, it keeps always a south-west direction, till it doubles the Cape of Good Hope, when it turns to the north-west, following the line of the coast. On approaching the equator it sets nearly west. When in the latitude of three degrees north it meets with another current, which has run southerly along the west coast of Africa, with which it unites, and crosses the Atlantic, nearly W. S. W. On reaching the Brazils, it diverges at cape St. Augustine into two streams; one going S. W. parallel with the coast till it doubles Cape Horn, where it meets the south polar currents. The other part of this great Atlantic stream proceeds in a northerly direction through the gulf of Glandín, along the shores of the United States, where it is called the Gulf Stream, to Newfoundland; and here it is backed by the north polar currents; takes an easterly course across the Atlantic, coming over to the coast of Norway and the British Isles, and turning thence to the south, through the bay of Biscay, and along the coasts of Spain and Africa, meets the great southern current in the latitude of three degrees north. The breadth of the African branch of this magnificent ocean river is supposed to be from 150 to 1000 miles. At the Cape of Good Hope it runs at the rate of about two miles an hour; at the equator three and a half; and in the Gulf Stream four miles an hour.

It may easily be supposed what changes must be constantly taking place in the bed of the ocean, and on the shores of the dry land, by the never-ceasing action of these currents, the force of which is too powerful to be more than slightly affected by the action of the tides or the winds. There is, probably, a great re-action also below the surface, and at greater depths than our limited observations can penetrate.*

* We may look for much interesting and useful information respecting the currents of the ocean, in a work now in course of

It such is the power and action of the currents and the tides in the earth, as it now is, we may safely conclude that they were not less active in the Antediluvian seas, the beds of which we now inhabit; having it thus in our power to examine the various strata of earthly debris, which, in the course of more than sixteen centuries, were deposited in various directions, according to the partial changes that must be constantly taking place in the direction of the currents, as the opposing points by which they are in a great degree guided, are worn away.

Having thus found one agent of sufficient power to remove vast quantities of mineral matter from the land into the ocean, and another, the effect of which is, gradually to arrange this matter in strata more or less horizontal, according to the form or slope of the primitive bed on which they are deposited, we can have little difficulty in accounting for most of the phenomena now discovered in the lower secondary formations of our earth. For the upper secondary formations and alluvial soils, we shall find a full and sufficient cause when we come to the consideration of the Mosaic deluge.

We must now resume the consideration of the primitive ocean from its first being "gathered together" until the Mosaic deluge, a period amounting to about 1656 years; and which will be found fully sufficient to account for many of the geological phenomena exposed to pur view. For when we apply to the utmost depths of secondary formations, the scale on which we are now considering the whole earth; and also when we think of the great extent of decomposition and reformation incessantly proceeding in our own times, we shall feel satisfied that the indefinite periods assumed by the chaotic philosophy, are infinitely greater than the existing phenomena demand; and we shall, consequently, have a more confirmed confidence in the truth of the inspired record.

publication, and written by the late Major Rennell. It is understood to apply, more particularly, to the currents of the Atlantic. *See page 42, and note, page 71.