conjecture what degree of velocity it is proper to ascribe to that motion of the waters, and what distances it may describe in one day. For, if there be selected, in order to form a judgment of this matter, some of those coasts which are less mountainous, or low lying, and which are contiguous to the open sea, and then the measure of the space of the globe interjacent between the extreme points of the flux and reflux, and that space be quadrupled on account of the four movements of the tide each day, and that number again doubled on account of the tides at the opposite shores of the same ocean; and to this number there be something added over and above on account of the height of the shores, which always rise to a certain elevation above the channel of the sea; that calculation will give the space which this sphere of water, were it free from obstruction, and moving in progression round the enveloped globe of earth, would describe in one day, which certainly would not be great.

Now, with respect to that difference which coincides with the measure of the moon's motion, and forms the period of a lunar month; we think that the explanation is this, that the period of six hours is not the exact measure of this reaction, just as the diurnal motion of any of the planets is not accomplished in twenty-four hours precisely, and least of all that of the moon. Wherefore, the measure of the ebb and flow of the tide is not a quarter of the motion of the fixed stars, which is twenty-four hours, but a quarter of the diurnal motion of the moon.

DIRECTIONS.

Let it be inquired, whether the hour of the tide on the coast of Africa be before the hour of tide about the Straits of Gibraltar. Let it be inquired whether the hour of the tide about Norway is before the hour of the tide about Sweden, and that, in like manner, before the hour of the tide at Graveling?

Let it be inquired, whether the hour of the tide on the coast of Brazil be before the hour of the tide on the coast of New Spain and Florida? Let it be inquired, whether the hour of the tide at the shores of China is not found nearly the same with the hour of tide on the coast of Peru,

and with the hour of reflux on the coast of Africa and Florida?

Let it be inquired, how far the hour of tide on the coast of Peru differs from the hour of tide at the coast of New Spain; and particularly what are the differences of the hour of tide at either shore of the Isthmus of Darien, in America; again, how far the hour of tide on the coast of Peru corresponds with the hour of tide on the coast of China?

Let it be inquired respecting the largeness of the tides on different coasts, not merely respecting their periods or hours. For, although the largeness of tides is generally caused by the depressions of the shores, yet, notwithstanding, they are closely connected with the true principle of the motion of the sea, according as it is favourable or adverse.

Let inquiry be made with respect to the Caspian sea, which is formed by considerable bodies of water locked up, without any outlet into the ocean, if they are subject to ebb and flow, and what? our conjecture being that the waters of the Caspian Sea may have one tide a day, not two, and such that the eastern shores of it are deserted by the sea, while the western are over flowed.

And let inquiry be made, whether the increase of the tide at new and full moons and at the equinoxes, takes place at the same time in different parts of the world, (and when we say at the same time, we do not mean at the same hour, for the hours vary, according to the rapidity of the waters' motion towards the shores, as we have said,) but in the same day.

Limits. The inquiry is not extended to a full explanation of the harmony of the monthly motion of the sea with the moon's motion, whether that takes place from a subordinate or a joint cause.

Relations. The present inquiry is connected with the inquiry whether the earth revolves with the diurnal motion of the heavens. For if the tide is, so to speak, the last stage of the gradual diminution of the diurnal motion, it will follow, that the globe of the earth is immovable, or at least that its motion is slower by far than that of the water. W. G. G.

VOL. III.-67

2 Y

But, seeing we are often at a loss for history and experiments, especially such as are luciferous, or instructive, and, as we call them, in

stances of the cross ;* by which the understanding might be helped in the knowledge of the true causes of things: we propose the task of making new experiments. These may serve as a history in design. For what else is to be done by us who are but breaking the ice?

For the mode of any more abstruse experiment, we explain it, lest any mistake arise about it; and to the intent, also, that we may excite others to excogitate better methods.

Also, we interspect certain admonitions and cautions concerning such fallacies of things, and errors in invention, as we meet with in our way. We subjoin our observations upon history and experiments, that the interpretation of nature may be the more in readiness and at hand.

Likewise, we lay down canons (but not such as are fixed and determined) and axioms which are, as it were, in embryo: such as offer them

* See Nov. Organ., 1. 2., Aph. 36.

Lastly we meditate sometimes certain essays of interpretation, though such as are low and of small advance, and by no means to be honoured (in our opinion) with the very name of interpretation.

For, what need have we of arrogance or imposture, seeing we have so often professed that we have not such a supply of history and experiments as is needful; and that, without these, the interpretation of nature cannot be brought to perfection. Wherefore, it is enough for us if we are not wanting to the beginning of things.

Now, for the sake of perspicuity and order, we prepare our way by avenues, which are a kind of prefaces to our inquisitions. Likewise, we interpose bonds of connection, that our inquisitions may not seem abrupt and disjointed.

Also, we suggest for use some hints of practice. Furthermore, we propose wishes of such things as are hitherto only desired and not had, together with those things which border on them, for the exciting the industry of man's mind. ·

Neither are we ignorant that those inquisitions are sometimes mutually entangled; so that some things of which we inquire, even the same things belong to several titles. But we will observe such measure, that (as far as may be) we may shun both the nauseousness of repetition, and the trouble of rejection, submitting, notwithstanding, to either of these, when, in an argument so obscure, there is necessity of so doing, in order to the more intelligible teaching of it.

This is the form and rule of our alphabet.

May God, the creator, preserver, and renewer of the universe, protect and govern this work, both in its ascent to his glory, and in its descent to the good of mankind, for the sake of his mercy and good will to men, through his only Son, Immanuel, God with us.

If there be made a turn-pin of any metal, after the fashion of a magnetic needle, and amber be applied to one end of it, after having been gently rubbed, the pin will turn.

Amber heated by the fire, be it warmish, hot, or set on fire, it does not draw.

A little bar of iron red-hot, flame, a lighted candle, a hot coal, put nigh sheaves (or straws) or turn-pins, (or compass needles,) do not draw. Amber, in a greater mass, if it be polite, draws, though not rubbed in a lesser quantity, and in a less polite mass, it draws not without rubbing. Crystal, lapis specularis, glass, and other such electric bodies, if burned, or scorched, draw not. Pitch, the softer rosin, benjoin, asphaltum, camphire, galbanum, ammoniac, storax, assa, these draw not at all when the air is hot: but when it is cooler, they draw weakly, and so that we can just perceive them to do so.

Reeking air, blown-up amber, &c., from the mouth, or from a moister atmosphere, choketh the attractive virtue.

If a paper, or a piece of linen, be put between amber and chaff, there is no motion, or attraction made.

Amber, or other electrics, warmed by the sunbeams, have not their attractive virtue so awakened, as by rubbing.

Amber rubbed, and exposed to the beams of the sun, retains its attractive force the longer; and does not so soon lose it, as it would do in the shadow.

applied to a shiver, or a compass-needle, draws best of all.

The electric virtue is as vigorous, for a time, in its retention, as it was in its first attraction. Flame (amber being put within the sphere of its activity) is not drawn by it.

A drop of water, amber being applied towards it, is drawn into a cone.

If electric bodies be rubbed too hard, their attraction is thereby hindered.

Those bodies, which in a clear sky do scarce draw, in a thick air move not at all. Water put upon amber choketh its attractive force, though it draweth the water itself.

Fat* so encompassing amber, that it toucheth it, takes away its attraction; but being so put betwixt it and the object to be drawn, as not to touch it, it doth not take it away.

Oil put upon amber, hinders not its motion. neither doth amber, rubbed with the finger moistened with oil, lose its attractive virtue.

Amber, jeats, and the like, do more strongly excite, and longer retain the objects they draw, although the rubbing be but little. But diamonds crystal, glass, ought to be rubbed longer, that they may appear hot, ere they be used for attraction.

Flames nigh to amber, though the distance be very small, are not drawn by it.

Amber, &c., draw the smoke of a lamp newly extinguished.

Sulphur, and hard wax, set on fire, do not draw.

Amber, when, immediately after rubbing, it is

when it ascends and becomes thinner.

A body drawn by electric bodies, is not manifestly altered, but only leans itself upon them.

For by Sarca, I suppose, he meaneth Sarcia.

Inquisition of the Conversions, Transmutations, Multiplications, and Productions of Bodies.

EARTH, by fire, is converted into bricks, which are of the nature of stones, and which we use for building, like stones. So with tiles.

Naphtha, which was that bituminous cement, wherewith the walls of Babylon were built, by time acquires exceedingly great hardness and firmness, equal to stone.

In clayey lands, where are pebbles and gravel, you shall find huge stones, concreted of pebbles and gravel, with stony matter interposed, as hard, or truly harder, than the pebbles themselves.

There are certain springs of water, wherein if you immerse wood, it shall be turned into the nature of stone; so as that the part sunk in the water shall become stone, the part above the water shall remain wood.

The viscous matter about the kidneys and bladder, in the human body, is converted into a pebble or stony matter. A stone, also, is often found in the gall-bladder; and sometimes, but this is most rare, in the vena porta.

Quære, how much time is required, that the matter of earth, in stone-quarries, may be converted into the stony nature?

Water, as there is reason to think, is changed into crystal; which may be seen in many caverns, where the crystal hangs in drops.

You may have an experiment of wood, or the stalks of plants, buried in quicksilver, whether they will harden, and, as it were, petrify, or no.

Report has much prevailed of a stone bred in the head of an old and great toad.

It is related that a certain nobleman, digging in the bed of his pool, found an egg turned into stone, the white and yolk retaining their proper colour; but the shell brightly sparkling, like a diamond exquisitely cut in faces.

Make experiment of some bodies, let down near to the bottom of a well, as wood, or other softer substances; but let them not touch the water, lest they rot.

They say that the white of an egg, through long insolation, or exposure in the sunbeams, has contracted the hardness of a stone.

Mud, in water, is converted in the shells of fishes, as in muscles,-(the fish) which are found in pools of fresh water, that flow not, and are covered with moss. But the substance of those shells is exceedingly delicate, clear, and glistening.