PER
PER
ciple, that the fame quantity of motion Is always preferved in the world.
Some have thought this augmentation no (mall difficulty againft thofe who maintain the moving force or power of action in bodies, to be proportional to their quantities of motion. This difficulty does not prefs the Leibnitians ; for it is to be obferv- ed, that notwithftanding the prodigious increafe of motion here afligned, yet there is no increment of the vis viva of this fyftem of bodies. Seethe articles Force and Visviva A learned author has urged, that if the force of bodies were in proportion to their quantities of motion, the increafe in the motion here mentioned might be employed to reftore the mo- tion of the firft body, and hence make a perpetual motion. But it is anfwered, that as the motion of the laft is increafed
. in the fame direction with the firft, the motion of all the reft will be in the contrary direction, and equal to that of the laft diminished by unity : hence the fum of the motions in the fame direction, remains as it did, equal to that of the firft and fmalleftbody, which we fuppofe unity. See Madaurin's Demonftrat. des Loix du choc des Corps, p. zi. Paris, 1724. and S. Grave/and. rem. fur la poflibilite du mouvement perpe- tuel in Journ. Liter.
It is to be obferved, that there is a limit which the velocity .communicated to the laft body never amounts to, (fuppofins; the firft and laft bodies, and the velocity of the firft before the ftroke, to be given) but to which it approaches continually, while the number of fuch bodies interpofed between the firft and laft is always increafed. And this limit is to the velocity of the firft body before the ftroke, in the fubduplicate ratio of the firft body to the laft. Mr. Huygens has not mentioned this limit, but the curious
, may fee the determination of it in Mr. Maclaurin's fluxions, art. 514. In the cafe mentioned by Huygens, this limit will be a number exprefTed by fourteen figures, for its logarithm is 1 4.. 9004850.
PERD1X, the part.idge, a bird well known and efteemed table, of which naturalifts enumerate five fpecies. 1. The common partridge. 1. The Brafilian partridge, called iambu, of a dufky yellow colour, fpotted with brown : of this there are two fpecies, a larger and a fmaller. See the article Iambu. 3. The perdix damafcena of Aldrovand, which re- fembles our partridge, but its feet are yellow and its beak lon- ger. 4. The red-legged partridge, common in France and Italy, and called there coiumo. SeeCoTUMO. And, 5. The Grascian partridge, which is twice as large as ours, and not feeming to differ from the cotumo in any thing but fize: they are all very finely tafted birds, but none are fo delicate as the cotumo* Rays ornithology, p. 119.
Perdix alba, the white partridge, a name given by many to the lagopus, a rough-footed bird of the gallinaceous kind, com- mon on the fnowy mountains, and by fome called the rabolane. See the article Lagopus.
Perdix marina, the fea -partridge, a name given by fome au- thors to the foal-fifh, from thefirmnefs and delicacy of its fiefii. Bellon. de Aquat. Vol. I. p. 34.
Perdix, in conchyliology, a name given by authors to a genus of fhells, fuppofed to referable the partridge in the fhades and difpofition of the colours.
Thepartridge-fhelt is of the dolium, or concha ghbofa clafs,, and is ftriated and fpotted in a peculiarly elegant and regular man- ner. See Dolium.
PERDONIUM, a term, invented by Paracelfus, to exprefs wine medicated with herbs.
PEREGRINATORES, in botany, a name for fuch ftudents in that fcience as have taken long journies, and vifited the remoteft regions, in fearch of plants. Linnasi Fund. Bot. p. 1.
PERE FERION, a name given by chirurgical writers to the perforating part of the trepan.
PERFECT, perfecli, in church hiflory, a defignation which the followers of Valentinus affumed tothemfclves. Hofm.Lex.'mvoc.
PERFOLIATA, the fame with bupleurum, or hare's ear ; a plant - recommended by authors asa vulnerary of thefirft clafs. Itisap- plied externally to contufions, frefh wounds, and luxated joints. There are many who efteem it a remedy even for the king's evil, and its virtues in the cure of navel- ruptures have lono- been famous : but all this wants proof. See Hare's ear
PERFOLIATE-/^/, among botanifts. See Leaf.
PERFORATA, in botany, a name given by fome authors to the hypericum, or St. John's wort, from the fmall holes feen all over its leaves, if held up to the light. Ger. Emac Ind 2
PERFORATUS (6>/.J-Perforatus brachii, in anatomy, a name given by Placentini to a mufcle of the arm, now gene- rally known by the name of the coraa-brachialU. It has been by many difputed not to be a diftinct mufcle. Vefalius calls it only pars intericris principii cubitum feclent'ium prhni car- noja, efteeming it only a part of that mufcle. Many of the writers who followed Vefalius have given it alfo the name of pars and portio, not efteeming it a diftinct mufcle : and Cafle- rius, who wrote after Placentini, calls it only portio carnofa, and cenfures that author for thinking it a diftin& mufcle, and calling it perforates.
TERIAMMA, a word iifed by fome medical writers to expref- an amulet.
PERIANTHIUM, in botany, exprefles that fort of cup which
confifts of feveral leaves, or elfe of one leaf divided into feve-
ral fegments, and furrounds the lower part of the flower. See
the article Calyx.
PERIAGOGE, nipaywyn, in rhetoric, the fame with peribole.
See the next article. PERIBOLE, a word ufed very frequently by Hippocrates, and in different places, in very different lenfes. Sometimes it fignifies a tranflation of the humors from one part to another; fometimes only the drefs or garments of a patient. In the firft of thefe fenfes, the word is frequently ufed to exprefs a tranflation of the morbific matter from the center to the fur- face, in the termination of a difeafe, by the breaking out of puftules all over the body. Periroi.e, IlsfijSo^, in rhetoric, is ufed where many things are accumulated into one period; which might have been divided into feveral. We have an inftance in Cicero's defence of Haccus : ^uodfi efj'et aliquayido futuru?n, ut aliquh de L. Flacci fermcie cogitaret ; nunquam iamen e\ijlimavi, Judices, Dechtm Ltelium, optimi vhi filium, optima ipfumfpe pr&ditum, Jumma dignitatis, earn fufcepturinn accufationem, qu<z fceleratorum potius civium odio, &furori 3 quam ipfius virtuti, atque injlituttz ado- lefcentitf, conveniret.
Now this long period might very well have been divided into the three following: 1. Quod fi efjet aliquandn futurum, ut ali- quis de L. filacci peruicie cogitaret j v.unquam tamen exijlimavi y judices, Dec'ium La/rum, earn fufcepturum accu[atione?n. 1. EJi e»im is optimi viri filius, optima ipfifpe praditus, fumma digni- tatis. 3. Accufatio vero hac fceleratorum potius odiu et furor i, quam ipfius virtut't atque injlituttz adolejcenticc, conven.ret. Fo/Tu Rhet. 1.6. p. 439- feq. See Punctuation, Cycl. PERICALAMITIS, in the materia medica of the antients, a name given by fome to the adarce.
We find the word pericalamitis in a defcription recorded ia Galen, and it has generally been underftood to mean flyrax, that being called calamita : but the adarce is the thing fionified by the name, which exprefles its manner of formation, it be- ing always found concreted about the ftalks of reeds that grow on the edges of waters. Galen 1. 1. See Adarce. ~ PERICARDIUM (Cyd.)— We read of a pericardium of a mon- ftrous fize, out of which above three pounds of coagulated blood and ferum were taken. See Medic. EiT. Edinb, Vol. V. art. 56. PERICARPIUM, among botanifts, a covering or cafe for the feeds of plants : it is the germen of the piftil enlarged. There are no lefs than nine fpecies of paricarpia : 1. A capfule. 2. A conceptaculum. 3. A pod. 4. A legume. 5. A nut. 6. A drupe. 7. An apple. 8. A berry. 9. A ftrobilus. See Capsule, Conceptaculum, &c. PERICHAREIA, a word ufed by the antients to exprefs a fud- den furprize of joy, fuch as has been frequently known to occafion death. PERICHRISIS, a word ufed by the antients for a liniment, principally of the oleaginous or fpirituous kinds, and as thin and fluid as oil. PERICLASIS, a word ufed by the antients for a fracture of a limb, attended with a large wound, by which the broken ends of the bone, or part of it, are laid bare. PERICLYMENUM, wood-bind or boney-fuckle, in botany, the name of a genus of plants, the characters of which are thefe : the flower confifts of one leaf, and is tubular, and divided into feveral fegments at the edges ; the cup finally becomes a round- ifh juicy fruit or berry, containing a comprefied feed of a rounded fhape.
The fpecies of peridymennm, enumerated by Mr. Tournefort, are thefe: I. The ever green Virginian long flowering peri- clymenum : and, 2. The yellow flowered Indian pcridxmenum. Tourn. Inft. p. 608. PERICNEMIA, a word ufed by fome medical writers for the
parts about the calf of the leg. PERIDONIUS lapis, in natural hiftory, a name given by fome of the writers of the middle ages to the pyriUs, which they call alfo perithe. PERIDROMIDES, EtyJ)»f&c, in antiquity. See Xysti. PERIDROMOS, a word ufed by the old Greek writers to ex- prefs the extreme edge of the hairs of the head, when hang- ing down in their natural form. PERIESTECOS, in medicine, an epithet for difeafes, figns,and fymptoms, which are falutary, and prognofticate the future better health of the patient. PERIGRAPHE, a word ufually underftood to exprefs a carelefs or inaccurate delineation of any thing : but in Vefalius it is ufed to exprefs the white lines or impreflions that appear in the mufculus rectus of the abdomen. PERILEUCOS, in the natural hiftory of the antients, a name given to an agate; but not of a diftinct fpecies, but only a particular appearance of the lead-coloured agate, more ufually known among them by the name of phaffachatss. See the ar- ticle Phassachates. PERINENEUCCS, an epithet given to a peculiar fort of irre- gular pulfe common in hectic patients, in which the artery beats more ftrongly in fome parts than in others. See the ar* tide Epineneucos.
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