in the fields, burdock, thiftles, and hemlock, grow on fuch foil to their largeft ftature. Clay, on the contrary, which is more difficult to diffolve, affords the low knot-grafs, swinecrefs, and the harder trefoils. Chalk, again, ftill more eafily diffoluble, nourishes a fpecies fomewhat larger; as the kidney-vetch, the refeda, and the campanulas: while Sand, however dignified by Linnæus, yields no nutriment at all to plants; thofe which are found on fandy foils being fed only by the loofe earth which happens to be among the fand. Hence poor fands afford fuch low plants as rupture-wort, and starved ferpyllum; and in others that have a little more earth, graffes or reeds, fhrubby heath, or the tall fox-glove. Thus no certain character can be given of the plants of fandy fods, because they depend upon the kind and quantity of real earth contained in the fand; which latter, the Doctor calls a debafed cryftal, indiffoluble by water.

Some Writers have been formerly of opinion, that pure water afforded nourishment to plants; our Author, however, tells us, "That they feed on nothing but earth; those which live in water being fed by the earth contained in that water; thofe upon rocks, by duft blown into their crevices, and wafhed down by rains: thofe upon walls, by the mould among the mortar; and even thofe on dunghills, by the earth mixed among the mafs; for abfolute dung will not fupport any plant beyond a fungus."

In treating of the effects of WATER in Vegetation, our Theorist observes its chief use to be that of a vehicle for the diffolved earth; which, without its affiftance, could not be abforbed by the pores, and conveyed to the feveral parts of the plant. It hath alfo a particular ufe regarding the exhalation of plants. "We think, fays he, fome plants will live in water, and others not: but all will do it, if the moist vapour they exhale be returned upon them."

On water thus evaporated, and thus received, he imagines, depends, in a great meafure, the peculiarity of certain plants being found in certain climates; and the fingularity abovementioned, respecting the difference of plants under the fame parallels of latitude. He fuppofes not only a certain warmth. in the air, but an appropriated conftruction of the parts of evaporation, requifite for this purpose: plants whofe leaves have the fame or a fimilar texture, being found in different countries under equal latitudes; but those which are particular in this respect, that is, perspiring more or lefs than the

ufual

1

ufual proportion, being to be found only in thofe places which, from the degree of moisture in the air, afford, under an equal heat, a proportional fupply. "Thus, continues our Author, Water is eminently concerned in that peculiarity of plants and places, the caufe of which must have been fought in vain, while the whole was attributed to heat. A proof of this is evident in thofe fpecies which live under water: for there evaporation and abforption being fmall and fimple, and the degree of heat tempered extremely by the depth, the fame fpecies are found in the most distant climates: thus the common yellow water-lilly, and the lentibularia, with feveral other English plants, which grow under deep waters, are found in China and the Indies." To prove that it is the ftate of the plant refpective to its evaporation, that occafions this, he adds, that the common fun-dew, whofe exhausted fluid is received again, is common alfo in the Indies.

Having thus confidered the effects of the elements, Fire, Air, Earth, and Water, in regard to Vegetation, our Author proceeds to fhew how thefe effects are diverfified by the Sea-" fons; treating alfo, in diftinct chapters, Of the Rife and Fall of the Sap, and Of the Fall and Permanency of the Leaf. On thefe fubjects he justly obferves, that what has been called the rife of fap into the trunks of trees in fpring, and its fall into the roots in winter, are in reality no more than the ascent of the juices in a greater or lefs quantity, proportioned to the warmth of the air: for that, there being no feafon in which there is not fome heat in the air, there is no time when fome fap does not rife; hence the branch of a vine which grows in the open air, near a ftove, being let into that warm place, will fhoot out leaves, bud, bloffom, and bear fruit, even in the depth of winter, while all the reft of the vine is naked.

With regard to the Fall of the Leaf, it is obferved, that if we would know why the quantity of fap which rises in winter, is enough to keep the leaves alive in fome trees, and not in others, we must seek the caufe in their juices and texture. Leaves fall, fays our Author, because the supply of juices from the root is not equal to the wafte by evaporation: and, therefore, thofe which perfpire or evaporate moft, will fall firft, and vice verfâ. It is not that the holly, for inftance, has more fupply from the root than the hawthorn, but it lofes lefs; which amounts to the fame thing. Thus deciduous-leaved trees become ever-greens in countries where the greater warmth of the air increases the fupply from the root; and in our own country the holly, and the like, retain their leaves,

because

because the fmall pores, and the thickened nature of the juices, prevent evaporation. The fap, when received at the root, is, indeed, thin and watery; but, by the time it reaches the leaves, it is affimilated, and becomes of the nature of the plant: therefore the tougher the juices are, the lefs fupply is required, as the lefs of courfe is evaporated. This we may fee illuftrated by a manifeft example in grafted and inoculated trees, where the ftock is a deciduous-leaved kind, and the graft an ever-green; as in the American oaks, which are ever-green; and yet when we raise them on the ftock of our own oak, which is deciduous, they yet retain their leaves all

winter.

From this general view of the Vegetable Economy, our Author proceeds regularly to fpecify the diftinét forms and fituation of the feveral parts of plants; on which the greater and leffer arrangement of clafs, order, genus, and fpecies are eftablished. He next enters on the feveral arrangements of plants, and exemplifies the different fyftems of botanical Writers; in all which, he fays, nature has been neglected, Previous, however, to a natural fyftem, he judges it expedient to form an artificial one, to affift the memory, and to enable a perfon unacquainted with botany, to find out an unknown plant as certainly as he would a word in a Dictionary. This is the defign of the prefent work, which, the Author thinks, may be more properly called a Botanical Index than a Syftem; being merely artificial, and intended to pave the way for a real fyftem, of a more natural kind than any which hath hitherto appeared in the world.

This being premifed, he goes on to defcribe the feveral plants, &c. in that order which he conceives beft adapted to the purpofes of his laborious undertaking; volume the fecond containing the whole feries of plants, with radiated flowers; volume the third, the entire claffes of plants with tubulate and ligulate flowers; and volume the fourth, the whole clafs of allociates or capitate plants.

In

To this account we fhall only add, that the defigns appear to have been accurately drawn, as the plates are well engrav ed. There is one advantage alfo in the fize of the figures, which botanical Writers have not always attended to. viewing herbs in their native beds, they are generally at ten or twelve feet diftance from the eye; whereas we ufually bring a book to within fix or eight inches of that organ. Rev. Dec. 1752.

Ff

For

For this reafon the fize of the figures in this work, is not what the parts would measure if laid upon the paper, but fuch as they fhew themfelves naturally while growing.

FOREIGN ARTICLES.

Principes de Morale, deduits de l'Ufage des Facultés de l'Entendement humain. Or,

The Principles of Morality, deduced from the Ufe of our intellectual Faculties. By Mr. Formey, Secretary of the Academy of Sciences and Belles-lettres at Berlin, and Member of the Royal Societies of London, Petersburg, Bologne, Gottingen, Greiffswald, Jena, Helmftadt, and Chalons. 12mo. 2 vols., Leyden. Imported by Becket and De Hondt.

TH

HIS work being dedicated to the Prefidents, Directors, and Fellows of the feveral Societies of which Mr. Farmey is a Member, it is with no impropriety we see a long ftring of literary titles, tacked to the well-known name of our Author. To do him juftice, however, he is not on other occafions, to be charged with the vanity of this ufelefs parade. We conceive alfo, it may be rather owing to the habit of writing, than the vanity of appearing as a Writer, that we are fo frequently called upon to mention fome new production of this indefatigable and multifarious Author. Having spent great part of his life in giving an account of the works of others, he may probably think it but reasonable, to put others to the trouble of giving an account of his; we muft own, indeed, it was with fome regret we faw Mr. Førmey relinquish the task of a Reviewer, for which he was fo well qualified, in order to fet up a book-manufactory of his own, when he could not be infenfible how plentifully the world was before provided. We do not, however, charge this laborious Academician with the production of bad, or altogether useless, books; he is undoubtedly a man of knowlege, and is no mean Writer. We must confefs also, that he appears in other refpects to much greater advantage in the prefent work than in moft of his other performances. Mr. Formey's greatest merit, and that no inconfiderable one in matters of science, is a ftrict attention to method, and a due regard to fyftematical confiftency. The want of the latter, he obferves, is a great defect in the celebrated Encyclopa,

which he hath occafionally furnished with a confiderable number of articles.

As it is impoffible for us here to enter into the plan of the work before us, we fhall difmifs it, with a caution to the Author; advifing him, the next time he takes upon him to cenfure fuch philofophers as Newton and Locke, to do it in a manner lefs exceptionable. He fhould confider the ftate of philofophy when thofe fuperior geniufes paved the way for its improvement, and that we are indebted, in a great measure, to them, for the means by which we are enabled to point out

their defects.

Du Contract Social; ou principes du Droit Politique. Par 7. J. Rouffeau. 12mo. Amfterdam, chez Rey.

Or, A Differtation on the Social Compact; or the principles of Politic Law.

HAT the importation of this little treatife, which was

first printed in Holland, should be prohibited in France, appears reasonable enough, on account of the republican principles it inculcates, and the freedom with which religion is therein politically confidered; but that fuch a work fhould be fuppreffed in a proteftant republic, that owes its very existence to fuch principles, and whofe profperity is in fo great a degree manifeftly due to an univerfal fpirit of toleration, is fomewhat furprizing. Yet, fo we are informed, it is; and it affords an instance of such narrow policy as plainly proves thofe, who practise it, either to be ignorant of the foundations of civil fociety in general, or falle to the true interefts of their own community in particular. But, be this as it may, it is with a fingular pleasure that we can recommend this exquifite little treatise to fuch of our own countrymen as would form a clear and unprejudiced view of the first principles of civil polity. Not that we think our Author perfectly right, or even altogether inconfiftent, in every thing he hath advanced. This tract, however, is written more methodically than is Mr. Rouffeau's general custom; nor does he appear to have compofed this piece, in his ufual negligent manner á baton rempu. Perhaps alfo the merit of the few fheets, of which it now confifts, is not a little enhanced by the number of thofe which he confeffes to have deftroyed; this treatife, we are told, being only an extract of a more comprehenfive work begun before the writer had confulted his own abilities, and on a better acquaintance with them, long fince abandoned.