those parts where the pressure is greatest, namely, in those where the moon is near the horizon. The sea, which otherwise would be spherical, upon the pressure of the moon must form itself into a spheroidal or oval figure, whose longest diameter is where the moon is vertical, and shortest where she is in the horizon; and the moon shifting her position as she turns round our globe once a day, this oval of water shifts with her, occasioning thereby the two floods and ebbs observable in each five and twenty hours. The spring-tides upon the new and full moons, and the neap tides upon the quarters, are occasioned by the attractive force of the sun in the new and full, conspiring with the attraction of the moon, and producing a tide by their united forces. Whereas in the quarters the sun raises the water where the moon depresses, and on the contrary; so as the tides are made only by the difference of their attraction. The sun and moon being either conjoined or opposite in the equinoctial, produce the greatest spring-tides. The subsequent neap-tides being produced by the tropical moon in the quarters, are always the least tides.

But then from the shoalness of the water in many places, and from the narrowness of the straits, by which the tides are in many places propagated, there arises a mighty diversity, which, without the knowledge of the places, cannot be accounted for.

Dr. Cheyne has taught me to take notice of one thing more. If our earth had any more than one moon attending it, we should receive probably a detriment from it, rather than an advantage. For at the conjunction and opposition with one anoth

er, and with the sun, we should have tides that would raise the waters to the tops of our mountains, and in their quadratures we should have no tides at all.

O my soul, beholding the moon above, look up to God, who hath so wisely proportioned her, for the designs on which He placed her there.

The sea is the grand fountain of those fresh waters, which supply and enrich the earth, and by convenient channels are carried back to the place from whence they came; how equally are these fresh waters distributed? how few Antigua's in the world? how agreeably are they disposed? and what a prodigious run have many of the rivers? The Danube, in a sober account, as Bohun computes, runs fifteen hundred miles in a straight line from its rise to its fall. The Nile, according to Varenius, allowing for curvatures, runs three thousand miles; and the Niger two thousand four hundred; the Ganges twelve hundred; the Amazonian above thirteen hundred Spanish leagues.

"But is it not high time for us to hear the voice of many waters!

"One celebrating the bounty of our God to us in the water, so expresses it: The contemplation may be carried to the element that is next above it."

Long since have we been taught such notes as these, "O Lord, how manifold are thy works! in wisdom hast thou made them all. The earth is full of thy riches. And so is the great and wide sea, wherein are swimming things innumerable.

"But can we look on the sea, and not see a picture of a troublesome world; see and be instructed."

APPENDIX.

WE can scarce leave the water without some remarks on our fluids; and we will be more particularly indebted to Dr. Cheyne for hinting them. How frugal is nature in principles, and yet how fruitful in compositions and in consequences! The primary fluids are but four, water, air, mercury and light. It is but seldom that three of these are much compounded with others. It is water alone, it is lymph, that is mostly the basis of all other mixtures; and it is the parts of solid bodies floating in this fluid that produce all our pleasant and useful varieties of liquors.

How vast the difference between the specific gravities of our fluids! Mercury is about eight thousand times heavier than air. Air must have choaked us, if it had been half so heavy as mercury.

And yet mankind in its present circumstances of the blood vessels, under frequent obstructions, could not well have done without such an heavy fluid as mercury.

All fluids agree in the condition of the direction of their pressure upon the sides of the containing vessel. This pressure is for ever communicated in lines perpendicular to the sides of the containing vessel. This beautiful and uniform property of all fluids necessarily follows from the sphericity of their constituent particles.

Our doctor's conclusion is as I would have it. "Now could any thing but the almighty power of God have rounded those infinite numbers of small particles whereof fluids consist? Or could any thing but his wisdom have assigned them their true dimensions, their exact weights, and required solidities?"

I beseech you, sirs, by what law of mechanism were all the particles of the several fluids turned of differing diameters, differing solidities, differing weights from one another; but all of the same diameters, and solidities, and weights among themselves? His is the finger of God! It is a just assertion of Dr. Grew, The regularity of corporeal principles shews that they come at first from a Divine regulater.

ESSAY XXIII. Of the EARTH.

THE Lord by wisdom has founded the earth. A poor sojourner now thinks it his duty to behold and admire the wisdom of his glorious Maker in it.

The earth, which is the basis and support of so many vegetables and animals, and yields the alimentary particles, whereof water is the vehicle, for their nourishment.

The various moulds and soils of the earth declare the admirable wisdom of the Creator, in making such a provision for a vast variety of intentions. God said, Let the earth bring forth. It is pretty odd; they who have written de Arte Combinatoria, reckon of no fewer than one hundred and sevFenty-nine millions, one thousand and sixty different sorts of earth: but we may content ourselves with Sir John Evelyn's enumeration, which is very short of that.

However, the vegetables owe not so much of their life and growth to the earth itself, as to some agreeable juices or salts lodged in it. Both Mr. Boyle and Van Helmont, by experiments, found the earth scarce at all diminished when plants, even trees, had been for divers years growing in it.

The strata of the earth, its lays and beds, afford

surprising matters of observation; the objects lodged in them; the uses made of them; and particularly the passage they give to sweet waters, as being the calanders wherein they are sweetened. It is asserted that these are found all to lie very much according to the laws of gravity Mr. Derham went far to demonstrate this assertion.

The vain colts of asses, that fain would be wise, have cavilled at the unequal surface of the earth, have opened against the mountains, as if they were superfluous excrescences; but warts deforming the face of the earth, and proofs the earth is but an heap of rubbish and ruins. Pliny had more of religion in him.

The sagacious Dr. Halley has observed, That the ridges of mountains being placed through the midst of their continents, do serve as alembics, to distil fresh waters in vast quantities for the use of the world and their heights give a descent to the streams, to run gently, like so many veins of the macrocosm, to be the more beneficial to the creation. The generation of clouds, and the distribution of rains, accommodated and accomplished by the mountains, is indeed very observable.

What rivers could there be without those admirable tools of nature

Vapours being raised by the sun, acting on the surface of the sea, as a fire under an alembic, by rarefying it, make the lightest and freshest portions thereof to rise first; which rarefaction is made (as Dr. Cheyne observes) by the insinuation of its active particles among the porous parts thereof, whereby they are put into a violent motion many different ways, and so are expanded into little bubbles of larger dimensions than formerly they