Q. What was Sir Ifaac Newton's opinion in regard to this affair? A. He affures us that this fecret power, which follicits bodies to fall towards the earth, acts lefs on them when at a greater diftance from it; he even goes farther, and lays down rules for making a proper eftimate of this diminution; and, as if he had carried the balance as far as the moon, he would have us believe, that a stone which fhould begin to fall from thence would fall to a certain height 3600 times flower than it does about the environs of the furface of the earth. And this is what this great philofopher has supported by proofs and demonftrations which can ftand the most rigorous teft. Q. Is gravity the fame in all parts of the earth? A. No; it is greater near the poles than near the equator. It is well known, by feveral experiments, that the pendulum must be fhortened in the countries near the equator, if it fhould be required to perform there its vibrations in as fhort a time as at London. Of CENTRAL FORCES. Q. What do you call central forces ? A. This name is given to the forces that produce the motion of a mobile, which tends continually to keep at a distance from the center of its motion, or to draw near it. Q. What is the centrifugal force? A. It is that whereby a mobile endeavours to keep from the center. Q. What is the centripetal force? A. It is that whereby a body is drawn or pushed towards the center. The centrifugal and centripetal forces are equal; for they act contrariwife, and deftroy one another. The mobile is with-held by its centripetal force in the curve, from whence its centrifugal force ftrives to remove it. The fling whirled about is equally tended on both fides, and the ftone ftrives to get away from the hand with the fame force that ftays it, or draws it back towards the hand. A body, thrown by a force which tends towards a center, moves in a plane paffing through the line according to which the projection is performed, and through the center of the forces. When a body moves about a center, and in moving draws nearer to this center, its motion is accelerated; and, on the contrary, retarded, if it goes from it. In order to affign the measure of central forces, it is neceffary to compare them together; for they differ not only in regard to the quantity of matter, but alfo in regard to the distance from the center, and the velocity with which bodies make their revolutions. Periodical time is that which is spent by a body in finifling an intire revolution about a center. The centrifugal forces of two bodies, which move with the fame velocity, and at equal distance from the center, are as their gravity. If two equal bodies have the fame periodical time, but different distances from the center, their centrifugal forces will be as the diftances from the centers. All bodies indifcriminately, in whatever ftate they may be, acquire a new centrifugal force in turning, Thus the circular motion is the fource of the centrifugal force and this force increafes in proportion to the velocity. The junction of the parts, or their fluidity, makes no alteration in this refpect. The examples of whirl-gigs, and the like, fhew us that the centrifugal force affumes an equilibrium with itfelf, in bodies whereof the axis, or center of gravity, does not circulate. The funs which are made to appear in artificial fires become greater and finer by their movement of rotation; for the inflamed falt petre is diffufed by an infinity of tangents, and forms a more extenfive plane than it would if it burned without turning. Mechanics have lately adopted the ufe of centrifugal forces: Pumps have been conAructed, wherein the centrifugal force is displayed in a very ingenious manner: On the fame principle forge-bellows have been made, and kinds of fieves, or winnowing vans for corn. The principal part of thete machines is an axis furnished with flyers, which are made to turn in a drum. Central forces are alfo of fingular ufe in phyfics, and more especially in aftronomy: The motions of the celestial bodies must be explained according to the principles of thefe forces. If the moon turns about the earth, and the earth itself and the other planets about the fun, the reafon is, because they all are follicited at the fame time by two powers; on one fide the centrifugal force, which results from their almoft circular motion, tends to keep them at a distance from the center of this revolution; on the oppofite fide they are with-held by a centripetal force, whereof the existence is acknowledged by all philofophers, though they are not agreed as to the nature of its caufe. If one of these two forces thould cease to act, thofe great moving bodies would either rush precipitately to the center of the world, or would lose themfelves in the immeality of the heavens. The The Compendious Syftem of NATURAL HISTORY, continued from Page 188 of the Twenty Seventh Volume. With the Coronilla Herbacea, or the Herbaceous jointed-podded Colutea, described and coloured from Nature; by Mr. Miller. HE fpecies reprefented in the annexed vario, or the herbaceous jointed-podded colutea, with a variable flower. a, fhews the carina or keel of the flower; b, the vexillum or flandard; c, the ftamina and pointal; d, the pod; and e, a fingle feed taken out of the pod. It hath a perennial creeping root, by which it multiplies fo faft, as foon to spread over a large tract of ground; therefore it is an improper plant for fmall gardens; nor fhould it be allowed a place in any garden, near other things, because it will foon spread over and deftroy them. But, as there are fucceffions of flowers from the beginning of June to the end of August on the fame plants, fo a fmall space may be allowed to this plant, in fome corner of large gardens, where better things will not thrive; for this is fo hardy as to thrive in any foil or fitu ation. This plant was formerly propofed to the curious in agriculture as a proper food for cattle, and a few perfons did make trial of it; fome of whom found, by experience, that it might be cultivated with great eafe, and become very beneficial to the farmer; but it was never extended very far: I fuppofe for the fame reafon as many other valuable things are neglected, only because they were not cultivated by their predeceffors. I remember to have feen a large fpot of ground planted with this at Deepden, near Darking in Surry, at a feat of the Hon. Mr. How ard; which, although it had been neglected for fome years after his death, yet was growing fo rank, as to spread over and get the better of all the rank weeds, brambles, &c. which had been permitted to grow among the plants. And I measured fome of the branches which I cut off, and found them upwards of five feet long, and very tender their whole length; fo that a small spot of ground will afford a good quantity of fodder for cattle, efpecially as it will grow fait enough to be cut five or fix times a year: And, in dry feafons, when there is a fcarcity of other herbage, this will be found an excellent plant to fupply the want. The cattle I have tried with this herb-green were horfes and cows, both of which feemed to eat it greedily: And there can be no doubt of its being a better food for any cattle than the common vetches, which are fown for that purpose; and, as this is an abiding plant, so it is much preferable to any which require to be renewed every year. The only objection, of any force, which I have yet heard made to the culture of this plant, is the difficulty of extirpating it when it is once planted; for the roots fpread more than couchgrafs in the ground. But, as the plant will last for ever, fo it fhould be always planted where it may remain; and, upon fuch land as is too dry to produce other herbage, this may be a very profitable plant. I have fome roots which have been planted above thirty years, and are in as great vigour as they were at first planting. This plant feldom produces much good feed in England, which may be accounted for from the roots creeping fo far into the ground; for many of the creeping rooted plants become barren as to feeds: But they propagate fo much by the root, as to fupply the want of feeds. The Hiftory of ENGLAND, continued from Page 87 of our laft. Every thing being ready for the projected expedition, the Prince of Orange went into the Affembly of the States-general, the 16th of October, 1688, to take a folemn leave of them. This was done in fo tender and moving a manner, that both himfelf and the States melted into tears. He imbarked the 19th of October, on a frigate of about thirty guns. The fleet confifted of fifty men of war, twenty-five frigates, as many firefhips, with near four hundred victuallers, and other veffels, for the transportation of above four thousand horfe and ten thousand foot. The most confiderable of the English, 3 who accompanied the Prince, were the Earls of Shrewsbury and Macclesfield, the Lords Mordaunt, Wiltshire, Pawlet, Elan, Dunblain, Admiral Herbert, Mr. Herbert, Col. Sidney, Mr. Ruffel, Sir Rowland Gwin, Major Wildmán, Dr. Burnet, Mr. Harbord, Mr. Ferguson, and many others lefs known. The Prince had with him, befides the Ge neral Officers of the Dutch forces, Count Schomberg, Marthal of France, who had laft ferved the Elector of Brandenburg; Count Charles, his fon; Monfieur Caillemote, younger fon to the Marquis of Rouvigny, and about three hundred French Officers This numerous fleet had been but few hours under fail, when fuddenly, the wind coming more wefterly, there arofe fuch a ftorm, that in less than two hours the whole fleet was fo difperfed, that the next day fcarce two fhips could be feen together. The ftorm continued two days, during which time, the ships endeavoured to gain, fome one port, fome another. Many were driven northward, and could not reach the appointed rendezvous till eight days after; nevertheless, the damage was so inconfiderable, that there was properly only lofs of time: But, on this occafion, the States made use of an artifice, which did the King great prejudice; they ordered the Haerlem and Amfterdam Gazettes to aggravate the damage fuftained by the fleet, and to infi nuate, that the Prince could not poffibly be in a condition to pursue his design till the next fpring. This was intended to amufe the Court of England, and make them more remifs in their preparations; but, besides this advantage, they received from this artifice another still more confiderable, which was, that the King, hearing the news with great pleasure, flattered himfelf, that he had now nothing more to fear, and that, before the fpring, he fhould infallibly be able to break all the Prince of Orange's meafures. In this belief, he revoked fome of his acts of grace granted to his subjects, and thereby clearly thewed, that thefe acts were extorted by neceffity, and that, confequently, no change was to be expected in his conduct for the future. It was in this critical juncture that Captain Langham, an Englishman in the fervice of the States, was feized on his arrival in England. In his portmanteau were found many copies of the Prince's declaration, which were fent to Court. The King, having read the declaration, was furprised at that expreffion, That the Prince was moft earneftly invited over by divers of the Lords, both fpiritual and temporal, and by many Gentlemen, and others.' Immediately he fent for the Archbishop, and four or five Bifhops then in London, and demanded of them, Whether the contents of the Prince's declaration, relating to their inviting him over, were true? The Biffiops contented themselves with promifing, in general, their faithful allegiance to his Majefty; but the King, little fatisfied with this anfwer, required them to juftify themselves to the world, as to their part in that invitation. At the fame time he fixed a day, whereon he obliged them to prefent a paper, under their own hand, fignifying their abhorrence of the Prince of Orange's intended invafion. He farther let them know, that a declaration was then in the prefs against the Prince of Orange, and was only deferred, to have their paper of abhorrence put into it." On the day appointed, the Bishops repaired to Whitehall, and, as foon as they were in the King's prefence, he called for their paper; but, with all fubmiffion, they begged to be excufed from writing any thing of that nature, and from making a particu lar defence to a general accufation, left they fhould give the first precedent of that kind against the privilege of Peers: Befides that, their profeffion being to promote peace, they thought it belonged not to them to de clare war, efpecially against a Prince so nearly allied to the Crown.' This answer threw the King into a violent rage; how ever, they perfifted in their refusal, in as dutiful terms as poffible. The King, not being able to prevail with them, ordered them to withdraw, with great indignation, They were afterwards informed, that one of the principal Members of the Council and Jefuited party advised the King to imprifon them all, and extort the truth from them by violence.' Mean time, the King, being defirous tó conceal the Prince of Orange's declaration from the people, forbad the publishing and difperfing it, by proclamation; but, being afterwards informed, that a great number of copies were handed about the kingdom, and fenfible that his prohibition would be to no purpofe, he chofe to print the declaration with remarks tending to justify his own, and render odious the Prince of Orange's conduct. About the fame time, was printed a letter from the Prince of Orange to the Officers of the English army, and another from Admiral Herbert to the English fleet. The defign of thefe two letters was the fame, namely, to inform the army and the fleet of the true intentions of the Prince, and to reprefent to them, that, in being the King's inftruments to accomplish his defigns, they were labouring their own ruin; wherefore the Officers, foldiers, and failors, were con jured not to fuffer therafelves to be abused by a falle notion of honour to ferve the King, contrary to the manifeft intereft of |