Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/209

 P E B

broken, but have been natural!/ formed of ttiis fhape; but it will be c-ahly {ten by any one who accurately Curveys their veins or coats that furround the nucleus, like the annual cirr eles of a- tree, that they mnft have been 'originally entire; and this will be the more plain if they are compared with a -ftone broken by- art. Such pebbbs as are found in ftrata, that lie near the furface of the earth, are much more brittle -than thofe which lie in deeper ftrata.

The more clear and tranfparent the fend is, which is found among pebbles, the more beautiful the pebbles are generally obferved to be.

The ufe of thefe ftones, and their difpofition in the earth, is a fubject of great admiration; and may ferve as one of the numerous proofs of an overruling Providence in the difpor fal of all natural bodies. The furface of the earth is com- pefed of vegetable mould, made up of different earth mixed with the putrid remaius of animal and vegetable bodies ; and is of the proper texture and compages for conducting the moi- fture to the roots of trees and plants : and under this are laid .the fands and pebbles which ferve as a fort of drain to carry off the redundant moifiure deeper into the earth, where it may be ready to fupply the place of what is conltantly rifmg in exha- lations; and left the ftrata of fand fhould be too thick, it is common to find thin ones of clay between, which ferve to put fome flop to the defcent of the moifture, and keep it from patting off too foon ; and left thefe thin ftrata of clay fhould yield and give way, and by their foftnefs, when wetted, give leave to the particles of fand to blend themfeives with, and even force their way through them, there are found in many places thin coats of a poor iron ore placed regularly above and below "the clay ; and by that means not only ftrengthening and fupport'mg the clay, but effectually keeping the fand from making its way into it. Phil. Tranf. N" 4S3.

Ridged Pebblfs. It is not uncommon to meet with pebbles in our gravel-pits which have one or more ridges, or white lines, landing above the furface of the reft of the ftone, in form of a rib or zone, laid on the ftone after its formation. This, however, is not the cafe; but the lime or zone always goes through the whole body of the pebble : the matter forming this ridge is always harder than the reft of the ftone ; and it feems probable, that at firft it was not extant or elevated, but level with the reft of the furface ; but being not fo eafily worn away by accidents, and when the whole pebble came in the way of rubbing among harder bodies, this would be lefs rubbed away, and confequently would be left more elevated than the reft. We daily fee on the fea-fhores numbers of ftones rounded by the continual rolling and tolling among the waves, and in thefe the fofter parts have given way firft and been worn into holes, while the harder have been left prominent. It feems probably to have been the cafe with thefe pebbles alfo ; but they are not found on the mores, but in our gravel-pits, at a great diftance from the fea : and it is evident, that thefe have had their furfaces thus ground and worn down between the time of their being formed by concretion in the waters of the deluge, and their being depofited where we now find them. This could only happen by means of the hurry and rapid motion of the waters of the deluge, at the time of their running off from the furface of the earth into the ocean or great abyfs, at the bottom of it: for, by numerous obferva- tions, it is plain, that the force of this water thus returning off from the earth was fo great, that in many places it tore up the folid ftrata, and wafhed off vaft manes from them, tumb- ling them afterwards along, and rounding. and fmoothing their furfaces in its paffage, and finally leaving them where its force began to abate. This we have inftances of in rdl parts of the world, and that fmaller pieces of ftone were thus rounded we fee in the cafe of thefe pebbles, the harder parts of which are left ftanding higher than the reft, and in many other the like inftances.

The fmoothnefs of the furfaces of fome pebbles and flints, which we find with their natural coats or crufts worn off, is another proof of the fame thing. Thefe pebbles, in this unna- turally naked ftate, as well as the ribbed and lineated ones, are found in our pits under the ftrata of earth ; and we doubt- lefs find them where they have lain undifturbed ever fince the time of their having been depofited there at the going off of the general deluge: and yet they are in exactly the fame condition with thofe which have been toffed about and round- ed on the fea fhores.

This is a plain indication, that they have been, before their being depofited there, toffed and rolled about in the fame man- ner with the others ; and there remains no time at which this fhould have been done, but that of the going oft' of the waters of the deluge, when a much larger body of water was evi- dently in a much greater agitation, and confequently could do in a very little time what we fee done on the fea fhores in a longer fpace

Swallowing of Pebbles. There are many people of opinion, that the fwallowing of pebbles is very beneficial to health, in helping the ftomach to digeft its food, and a pebble poffet is an old woman's medicine in the colic in many parts of England. They ufually order the fmall white ftones to be picked up out »f gravel walks for this purpofe, and eat them in large quan-

PEC

titles in fome fort of fpoon meat* of which milk is art iri» gredient.

rhe thing that has given occafion to this praaice feems to have been, that people oblcrve the birds to pick up the gravel; and that they are never well nnlefs they have fiequent re- coiirfe to this to help their digeflion : but this is no fimilar cale at all, for the gizzard or ftomach of a bird is made very Itrong, becaufe the creature hath no teeth to chew its food • and this gizzard is lined with a rough coat, by the help of winch and thefe ftones, the food they fwaliow whole is fd ground, as to yield its juices to the nourifhment of the ani- mal. But the ftomach of man is formed fo very differently, that it can never require thofe affiftances to the comminution ot food. Many people have, however, accuftomed themfeives to lwallow not only thefe fmall white ftones, but large pMlis, ever, to the fize of a walnut each 5 and thefe will often pafs lately, and people who have long accuftomed themfeives to lwallow them, boaft of receiving no injury from them: we can never know, however, that the death of fuch perfons is not owing to them at laft ; and as they can do no good, it is beft always to avoid them. There is one inftance on re- cord, of much mifchief done by them; this is in ourPhilo- fophical Tranfaclions. Phil. 1 ranf. N= 25,, p., Q0. Amanofabouttwenty-feven years of age, and lean habit, had been ufeJ for three years before to fwaliow round while pebbles, as a cure for fome windy diforders to which he was fubj<-a, and they ufed to pafs thro' him eafily, and give relief for the time, in one of his fits, at the end of this time, having fwallowed hisufual number, which was nine, and they not palling thro' him, he fwallowed more and more, to the number of two hundred. None of thefe p-afTed off at the time, nor even in the fpace of two years and an half; at the end of which time he applied for relief in a miferable way : he could digeft no food, but vomited up all he fwallowed. On examining his belly the ftones were found lodged, not in the ftomach, but almoft as low as the os pubis ; they might be felt with the Hand thro the integuments, and rattled as if in a bag ■ if the man was hanged up by the feet to a ladder for a fmall fpace ot time, they would get up into his ftomach again ; but upon fettmg him on the ground they would foon falfinto their

}-J ™ e ', and that fo P lainl >' t0 the fenfe > that th! =y might be diltinclly heard and counted one by one. If his body was not axative, he certainly vomited all he eat ; if it was, he had a little refpite at times; and as he lay in bed he could perceive the ftones alfo higher than their ufual place, and (rive him great difturbance. He was on thefe occafions always forced to get up, and on ftanding or kneeling he could perceive them fall down into their old place again, and could count them as they fell. He ufually on thefe occafions could count more than an hundred : at length he became unable to work or move for them, and voided large quantities of blood by ftool, after difturbing them by any violent motion. The ufe of proper medicines relieved him in many of thefe fymptoms, but no means ever made ufe of was able to carry off one finds ftone. °

PECHEM, in the materia medica, a name given by the modern Greek writers to the root called behem by Avifenna and Se- rapion. Many have been at a lofs to know, what this root pechem was ; but the virtues afcribed to it are the fame with thofe ot the behem of the Arabians ; its defcription the fame, and the divifion of it into white and red, is alfo the fame as that of the behem. Nay, the word pechem is only formed of behem, by changing rhe E into a P, which is very common, and the afpirate h into x, or ch, which is as common. Myrepfus, who treats of this root, fays the fame thino- that the Arabian Avifenna fays of behem, namely, that it°was th« fragments of a woody root much corrugated and wrinkled on the furface, which was owing to its being fo moift whilft frefh, that it always fhrurik greatly in the drying.

PECHYAGRA, a name given by authors to the gout affeain? the elbow.

PECHYS, a name ufed by fome anatomical writers for ths elbow.

PECHYTYRBE, an epithet ufed by fome medical writers for the fcurvy.

PECORA, loch, in the Linnasan Syftem of zoology, a claflical term, comprehending a whole order of quadrupeds. The charaflers of this order are, that the creatures have dates in- cifores, or cutting teeth, in their under-jaw, but none in their upper: they have no canim, or dog-teeth, and have five mo- lares each way. The paps of this order of animals are fi- tuated in their groin, and their feet have hoofs. Of this or- der are the camel, ftag, goat, fheep, and ox. Lhmai Svft. Nat. p. 41. '

PECTE, in botany, a name given by fome of the old Greek writers to the great cemfry, called alfo ojppagina, from its ag- glutinating broken bones.

PECTEN (Cycl) in natural hiftory, the name of a genus of, fhell-filh, the charaacrs of which are thefe: it is a bivalve fhell, (hutting clofe in all parts, of a flatted fhape, ftriated in the manner of a comb, and often auricuiatcd, fomctimes Shi* femiauriculated,and in fome fpecies not auriculatedatall There are alfo fome few fpecies whh h are elate, not flat as the others

TtK