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After having made this discovery, as our author says, with furprize (at which we are not fuprized, confidering it was fo furprizing a difcovery) he proceeds to tell us, that he was no fooner convinced of the falsehood of the system generally received than he thought it incumbent on him, if poffible, to discover the true fyftem of nature, in order to fill up the vacuum he had left in his own mind. To this end, we are told, he applied himself to that experimental knowledge, by which only the general scheme or plan of nature in this material world is to be known, and by fimply attending to fact and reality, drew the outlines of the draught here presented to the public.

Before Mr. Usher lays down his own system, however, he give his readers, what he calls, a miniature idea of the fyftem he attacks,

"Mechanic philofophers, fays he, fuppofe all the parts and particles of matter to be homogenous, and to differ from each other in their shapes, fizes, and motions only; and that natural bodies being formed by the concourse and convention of the minute particles of matter, the whole variety we observe in natural bodies, is the mere result of the shapes, fizes, texture, motion, and reft of the minute and insensible corpufcles of which the particular bodies are compofed.

"This doctrine they pretend to derive from fimilar effects in objects of sense, and to establish on analogy or a parity of reasoning. We fee, Say they, a piece of iron, by a change in the form, become a new thing, i. e. a knife, and acquire a new capacity of cutting and feparating other fubftances: a piece of glafs or refin, by a motion which beats it into powder, is deprived of its tranfparency, and becomes white; a piece of filver, by being burnished, lofes much of its former colour, and acquires a new power of reflecting the beams of light, and vifible objects, in the manner proper to fpecular bodies; yet all this is done by the intervention of a burnishing pool, which often is but a piece of steel

or iron, conveniently shaped; and alf that this burnisher does, is but to deprefs the little prominences of the filver, and reduce them, and the little cavities. of it, to one phyfically level, or plain fuperficies.

From phænomena, fay they, we may proceed to establish general rules. When we see these changes produced in bodies by mechanic alterations, we are authorized to conclude universally, that alike effects will proceed from the fame caufe; and by the most rational and unexceptionable analogy in the world, to lay it down as an axiom, that the fhapes, fizes, texture, and infenfible motion or reft of the invisible corpuscles, determine the body, compounded of them, to be this or that particular thing, viz. a stone or an apple-tree, gold or sea-water.'" In order to explain this hypothefis, they affert, as I obferved before, that all matter is homogenous, and that though it may be conceived as infinitely divifible, (and would really be fo by an agent of infinite power) yet, in the present state of things, it is reducible, by natural agency only, to certain very minute corpufcles; beyond which, there is no physical poffibility of subdividing it farther; that each of those corpufcles are of some determinate bulk and figure, and capable of different degrees of motion; and that accordingly as these corpufcles happen to convene, they form an oak-tree, a cloud, or a rock; which differ only in the mechanism of their constituent particles. So that the refult of the corpufcularian philofophy, is, that fize, shape, motion, or reft, are the catholic, primary, or radical properties of bodies; and that the other properties, as colour, tafte, fmell, &c. arife out of them, as fecondary qualities, or mere effects.'

Such is our author's abitract of the mechanical philofophy: the whole fyftem of which he invalidates at once, by the following fhrewd and conclufive reflec tions.

"The fuppofed analogy, or parity of reason, which is the whole fupport of this fyftem, upon examination, ap

pears

pears to be fallacious and groundless;
the iron of the knife is not changed or
transmuted, it is only flatted and ground
to an edge: the glass or refin pulveriz-
ed, are still real glass and refin, mingled
with particles of air, and thereby ren-
dered white, as water is in foam; and
burnished filver, is filver ftill: they are
all the fame identical natural bodies,
and of the fame real fpecies they were
before this egregious mutation; and
therefore the true confequence, from
thefe inftances, is, that the different
kinds of natural bodies, are not the re-
fult of infenfible fhapes, fizes, or moti-
ons, or of any mechanic quality what-
ever; and that there is no analogy in
nature, that leads to fuch a prefumption.
"I must request of any perfon, who
takes up his pen for the mechanic fyftem,
to point out one single instance in na-
ture, of a tranfmutation wrought in a
natural body, by an alteration in the
vifible and known fhape, fize, or mo-
tion of that body. This is a request he
cannot with any reafon deny me, if he
attempts to fupport his theory on ana-
logy, or parity of reasoning; but if he
gives up the analogy, by producing no
fuch tranfmutation, then I defire, he
will fhew any other foundation for his
system; and even make it appear, that
it is poffible to conceive, that any varia-
tion of shape, fize, or motion, can na-
turally and spontaneously, cause this, or
that particular odour, tafte, or colour,
preferable to any other. Thus I have
pointed out the only ground on which
a mechanic philofopher may folidly an-
fwer me; but let it be remembered, that
I proteft in form, against his producing
instances, where the tranfmutation is
not real, and then making a tranfition
to the new productions of nature; and
fuppofing, instead of proving, that they
are effects of alterations, in thape, fize,
or motion. The ufual changes made
by mechanifm every day, from the eafe
with which they are conceived, are very
apt to cheat us into a belief, that real
essential transmutations are equally ef-
fects of the fame caule. Mutations, in
this tract of thought, are familiar it is
rue; fo are dreams, and the thousand

caftles built every day in the air; but Ţ infift on it, that this familiarity gives us no right to flide in, by a philofophic legerdemain, an analogy that does not subsist in nature, and after, to make a real foundation for science on that fan. ciful analogy."

In

The reader will fee that our new the orift is a bold man ; his taking upon him to challenge his adversaries, and to mark out the ground on which he is to be attacked, may be thought, however, rather too bold and peremptory. deed a mechanic philofopher with a very small share of logic, might object to' him the-fophiftry of denying that any analogy subsists between artificial bodies and natural bodies, because natural bodies are not changed and diversified fo palpably as artificial ones. He might fay, no mechanic philosopher ever pretended that any alteration in the vifible and known shape, size, or motion of a natural body, could change the specific substance of that body. To be ferious, no one ever faid, that by giving a piece of steel that form, which converted it into a knife, or a razor, he thereby altered the qualities, or changed the fubftance of the steel.

The qualities of the knife, or razor, however, are certainly owing to the alteration of the form of the fteel: nor do we fee any abfurdity in concluding from analogy, that as the qualities of artificial bodies, evidently depend on their visible shape, fize, or modification of parts, fo may the specific qualities of natural bodies, depend on the invisible and impalpable shape, fize, or modifica tion of their parts likewife. Our not being able to trace minutely the mechanifm of natural bodies in their formation or tranfinutation, is nothing to the purpose: indeed if we could, we should have no need to reafon from analogy on this fubject at all: so that Mr.. Usfher here objects to the use of analogy, without our having fuch a knowledge of things as would entirely set it afide, and render it useless.

But let us attend to our author's own fyftem.

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"I have concluded, fays he, from an attention to well known effects evident to fenfe, which I have placed in my reader's view, that the fimple elements of bodies are ingenerable, unchangeable, and incorruptible, and were at the beginning created different, and divided into kinds or forts; that the embryoes, or feeds of natural bodies, are select compofitions of thefe elements, which inherit in themselves, by a divine law, principles productive of new feeds and embryoes,that continue and eternize the fpecies by fucceffion; that each kind of element being endued with particular attractions and repulfions, the fpecific feeds convene, and confolidate to themselves, their respective kindred and family elements, and refift and repel the unrelated and diffociable ones; whence in the natural round and courfe of attractions and repulfions, the pro ductions and diffolutions we fee in this tranfitory world, take place."

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Such is the author's account of the fyftem he attacks, and of his own. In combating the former, however, we do not think him fo fair and candid as we could have wifhed. In particular he tell us, that, "Whether a mechanic philofopher avows it in exprefs terms or no, it is an unavoidable and fundamental part of his hypothefis, that the kinds of bodies that form the world, and confequently the amazing and beauteous order thereof, are the effects of the undirected concourse of particles of various fhapes, fizes, and motions. "When a philofopher gravely tells us, that the fun, the moon, the stars, and this habitable globe, with all its wondrous progeny, where every fingle body hath fuch amazing traces of fuperlative wisdom and power, are formed in confequence of the mere shapes and fizes of the conftituent particles jumbled together; and relates a thousand times more violent and numerous metamorphofes than thofe of Ovid, with out the poet's probability of introducing a God equal to the work; I fay, when a philofopher tells us this wondrous tale we listen to the venerable fage

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with applaufe, and swallow down the ftupendous legend for knowledge and learning. I can affign no reason for this credulity, but that the doctrine is beyond all limits of common fense; for there is a certain noble heighth in extravagance, to which if once we be able to carry our fyftem, it becomes free from all examination or trial, like the countries on the furface of the moon; and if we be lucky enough to make a few converts of note, then it may pass freely upon the millions who judge only by precedent "

What is this but to tell us, that all mechanic philofophers must be atheists? A most egregious and scandalous falsehood! Nor doth this author deal more candidly with the mechanic philosophy itself than with its profeffors; endeavouring throughout his whole pamphlet to mitrepresent or misapply the most common arguments and illuftrations of his opponents; all which, however, ferve rather to ftrengthen their cause than his own.

We fhall give the reader a short specimen or two of the expedients which this writer hath fubftituted, instead of the homogenous particles, to account for the phænomena of bodies.

Nothing hath more puzzled the philofophers of the prefent and last century, than to account for the cohesion of the parts of bodies. Mr. Usher, however, hath wiped off the difficulty with a wet finge letting us at once into the whole fecret of cohefion, and the procefs of fertilization in the mineral and vegetable kingdom. Doth any body afk, what makes the parts of bodies adhere together?

"Clay, fays Mr. Usher, is the common bafis, and unchangeable unfleeting confiftence, that confolidates all vegetable and animal bodies, which gives them ftability and fixednefs, and remains naked to the eye, when the volatile and fpecific elements are transpired and fled.

As fome elements are much lefs volatile than others, and recede more leifurely, the caput mortuum, or clay of corrupted bodies, differ in their

qualities.

qualities for fome little time, but at length, by their final egrefs, the deferted clay becomes of the nature of the foil it lies on.

"The clay of perished bodies deferted and ftripped, difcovers itself, and puts on his priftrine form once more; while the tranfient and volatile elements, that have broke their bonds and efcaped, mingle with the circumfluent atmosphere, where they are fcattered by the action of the fun, till they impregnate the whole fluid with the feeds of life. In process of time, being abforbed by the rarified vapours, and the clouds that fcour the regions of the air to and fro, they defcend in prolic fhowers and dews, and make the fmiling earth teem with plenty and beauty. Ele ments of a different nature, that are not arrested by vegetables, enter with the rain into the fiffures of the earth, and lodging in masses, proper for their reception, form metals, ftones, and other foffils. Whence it has happened that shells of fishes, ears of corn, plants, and leaves petrified, are found fometimes in the hearts of blocks of marble; and that columns of stone have been discovered irregularly fluted, like icicles, pendent from the roofs of grottoes, and fubterraneous caves, made by the flow dropping of water, that brought ftony particles along with it in fucceffive layers. Pure clay is wholly barren. The fertility of the earth is a foreign, alienable acquifition, by no means permanent in the foil, as appears from the changeable state of lands fhirting from fertility to barrennefs, and from barrenness to fertility; this truth alío is evident from the whole practice of agriculture."

As clay, according to our author, binds the parts of bodies together, fo water and fite are the agents which feparate them. Hear what he fays on this head, and at the fame time let this paffage serve as a fpecimen of Mr. Usher's tile, which as far furpaffes that of our mechanic philofophers, as his fyftem is fuperior to that of Newton, or any other of the corpufcularian tribe,

"Water adheres to, and cements the minute and fugitive particles of bodies. Fire gives them elasticity, and rends them asunder. It is, probably, by the cohefion of water to the corpul cles of the groffer elements, and by its levity, when rarified, they become fugitive The fire evaporates the water, and wings away the minute particles that cohere to it, upon the ætherial wings of the liquid element into the atmosphere; by which œconomy it for ever replenishes the inexhaustible stores of nature, and fupplies the wardrobe of fucceffive fprings. The cohesion of water to the elementary particles of bodies occafions the drying of winds; for those invisible atoms fanning the furface of the earth and waters, dip their wings in the liquid wave, and carry off the imperceptible dew-drops by fucceffive millions.

"The joint operation of fire and was ter feem necessary in the diffolution and vegetation of bodies; or rather the miniftry of the water, when it is animated and put in motion by fire. The power of moisture and heat in combination, are known to every body in vege tation; but that combination is also equally neceffary in the diffolution of bodies. Flesh does not corrupt in frolly weather: the carcafes of men are found whole and fresh on the Andes, fecured. in eternal frost. In hot and dry countries, where the moisture is exhaled from the flesh, we find nearly the fame effects; the bodies of men are tolled about in Arabia, in the deserts of Afri-' ca, and the fouth part of Perfia, whole and inoffenive of fmell, for years, perhaps for ages, embalmed in ærherial fires. The aduft climate of Upper Egypt, has contributed more to the prefervation of the bodies of their dead, than their fpices and balsams. Heat and moisture in concert awaken all the elements to life and action, and that action in courfe produces vegetati on and corruption. Let me here deplore our ignorance of the nature of thofe two diftinguished elements, and the attachment of mankind to that bir

ren

ren philosophy, which, by turning the attention of the learned to the trifling powers of mechanism, bound down all genius, and laid an arrest on the knowledge of nature, except what is merely acquired by accident."

After entertaining his readers with a good deal of this kind of reafoning, Mr. Usher stumbles at length on fomething like a truth, which is," that the fyftem he has been endeavouring to trace is not NEW, but of all others the most ancient; and had fallen into oblivion, before the other ancient theories were thought on, much about the time mankind unfortunately loft fight of their own origin, and funk into endless errors." The expedient indeed of recurring to specific forms, qualities, and elements, is of too ancient a date, and favours too much of the days of ignorance and barbarism, to be adopted in thefe more enlightened times of mechanical reasoning and philofophical experiment.

From the GENTLEMAN'S MAGAZINE.

An Account of the Sheep and Sheep

Walks of Spain concluded.

T the latter end of September

A they put on the redding

it is a ponderous irony earth, common in Spain; the fhepherd diffolves it in water, and dawbs the fheeps backs with it from the neck to the rump. It is an old cuftom. Some fay it mixes with the grease of the wool, and fo becomes a varnish impenetrable to the rain and cold; others, that its weight keeps the wool down, fo hinders it from growing long and coarse; and others, that it acts as an abforbent earth, receives part of the tranfpiration, which would foul the wool, and make it afperous.

The latter end of September the sheep begin their march towards the low

plains; their itinery is marked out by immemorial cuftom, and by ordinances, and is as well regulated as the march of troops. They feed freely in all the wilds and commons they_pass through, but as they muft neceffarily pass through many cultivated spots, the proprietors of them are obliged by law to leave a paffage open for the fheep, through vine-yards, olive-yards, corn-fields, and pafture land commen to towns, and these passages must be at least 90 yards wide, that they may not be too crowded in a narrow lane. These passages are often fo long, that the poor creatures march fix or seven leagues a day to get into the open wilds, where the fhepherd walks flow to let them feed at eafe and reft; but they never stop, they have no day of repose, they march at least two leagues a day, ever following the shepherd, always feeding or feeking with their heads towards the ground, till they get to their journey's end, which, from the Montana to Extramandura, is about 150 leagues, which they march in less than 40 days. The chief fhepherd's first care is to fee that each tribe is conducted to the fame diftrict it fed in the year before, and where the sheep were yeaned, which they think prevents a variation in the wool, though indeed this

rious truth that the sheep would go to that very spot of their own accord. His next care was to fix the toils where the fheep pass the night, left they should ftray, and fall into the jaws of wolves. Laftly, the shepherds make up their poor huts with ftakes, branches, and brambles, for which end, and for firing, they are allowed by the law to cut off one branch from every tree; I believe this to be the reason that all the forest-trees near the fheep walks in Spain are as hollow as willow-pollards. The roots of trees and the quantity of fap increase yearly with the branches; if you lopp

The Toils are made of Sparto, in meshes a foot wide, and the thickness of a finger, fo that Toils ferve inftead of hurdles. The whole fquare Toil is light. Sparto is a fort of rush which bears twifting into ropes for coafting veffels. It fwims; hemp finks: It is called Bofs by the English failors.

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