PER
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PET
Perspective 'Plane, is a Glafs, or other tranfpatent Sur- face, fupposVI to be placed between the Eye and the Ob- ject, Perpendicular to the HorizGn, unlets the contrary be ex- prefsly mcntion'd. See Plane.
Such is the Plane, ///(Fig. if.) between the Eye and the Object AS C, cutting the optic Rays in a, b, c.
This, fome call the Section ; Come the 'table, and others the Glafs. See Section.
. PERSPIRATION, in Medicine, the Action of evacuat- ing the Juices of the Body, through the Pores of the Skin. See Evacuation, Pore, and Skin.
When this Evacuation is copious enough to be perceiv'd by the Senfes, as in fweat, the Perforation is faid to be fenfi- ble ; where it efcapes the Notice of the Senfes, as is the Cafe in the ordinary State of the Body, the Perforation is faid to be infenfible. Sec Sweat.
The Word 'Perforation ufed fimply, and without any Ad- jective, is underliood of infeniible 'Perspiration, Sanclcrius, the great Paduan Phyfician, was the Firft who took Notice of this Evacuation : To him we owe both the Invention and Perfection of the Doctrine of infenfible Perforation.
The Veffels thro' which rhe 'perforatum is perform'd, lye obliquely open under the Squama: or Scales of the Cuticle or Scarf skin. They are inconceivably fmall : From a Calcu- lation of Leewenhoeck, it appears that the Months of 125CCO of 'em may be cover'd with a common Grain of Sand. See Cuticle; Miliary Gland.
Thro' thefe Veffels is continually tranfuding a fubtile Humour, from every Point of the Body, and throughout the whole Expanfe of the Cuticle.
The Matter evacuated this way, is found by fure Expe- rience to be more than equal to that evacuated all the otner Ways, i. e. by Stool, Urine, gjfe. Saniiorius found in Italy, un- der the Circumstances of a moderate Diet, middle Age, and eafy Life, that the Matter infenfibiy perfpired was f of that taken in for Food : fo that there only remain'd \ for Nutri- tion, and the Excrements of the Nofe, Ears, Intcftines, Bladder, g?C See Excrement.
The fame Author thews, that as much is evacuated by in- fenfible Perforation in one Day, as by Stool in fourteen Days ; particularly, that in a Night's Time, about fixteen Ounces is ordinarily fent out by Urine, four Ounces by Stool; and above forty Ounces by infenfible Perforation.
He alfo obferves, that if a Man eat and drink 8 /. in a Day, 5 /. of it is fpent in infenfible 'Perforation ; and adds as
- o the Times, that within 5 Hours after eating there is per-
fpired about 1/. from the 5th to the nth Hour about %l. and from the 12th to the 16th fcarce half a Pound.
The Benefits of infenfible Perforation are fo great, that without it, Sorelli fays, animal Life cou'd not be pre- fer v'd.
The great Subtility, Equability, and Plenty of the Matter thus .perfpired, its Increafe after Sleep, S?c. conftitute the grand Symptoms of a perfect State of Health ; and the chief Means of prefcrving the fame. See Health.
On the contrary, the departing from thefe is the firft fure Sign, and perhaps Caufe, of Difeafes. See Disease.
Perforation is performed, preferved, and encreafed by the Vifcera, Veflels, Fibres; by Motion or Exercife as tar as the firft Appearance of Sweat, by moderate Ufe of Venery ; Sleep of 7 or 8 Hours, the Body well cover'd yet not loaden with Bed-cloaths, Chearfulnefs, light fermented yet folid Food, notFat; pure, cold, heavy Air, &c.
The contraries of all thefe, as alfo the Increafe of the other Excretions, diminifh, prevent, deprave it.
Hence we fee the Caufe, Effect, iSc of this perfpitable Matter, its Ufe is preferving the Parts foft and flexible, in fupplying what's loft, but chiefly in preferving the nervous Papilla; moifl, frefh, lively, fit to be affected by Ob-jeds, and to tranfmit their Impreffions. See Nerve, Sensation, $$c.
Too much Perforation occafions weaknefs, fwoonings, fudden Death ; too little or none at all occafioris the Veficles to dry, wither, and perifli. Hence alfo the larger Emunc- tories, come to be obftructed ; hence the Circulation is dif- turb'd, fharp Humours retain'd ; hence Putridity, Crudity, Fevers, Inflammations, Impofthumes. See Disease.
To determine the State and Conditions of the 'Perforation, fo neccflary for iudging of thofe of the Body, SanBorius in- vented a ixeighwg Chair, whereby he cxamin'd the Quanti- ty, Degree, gfc. of Perforation in feveral Circumftances of the Body, under feveral Temperatures of the Air, in the fe- veral Intervals of eating, drinking, Deeping, &c. See Weigh- ing Chair.
Some of the more extraordinary Phienomena obferv'd here- with, are; that for fome time after eating the Perforation isleaftofall. That between the 5th and 12th Hour after Meals Perforation is greateft. That riding either on Horfe- back, in a Coach, or Ship, GJr. brisk Motion on the Ice, £=?c. but above all, a brisk Friction of the Skin ; promote 2><;r/J>tr«fto«furprifingly. That in fweating the Perforation is much lefs than at other Times : And that 'Perforation is al- ways much lefs in Women than Men,
PERTICA or Perticata term, in our old Law Books, is the fourth Part of an Acre. See Rood.
Conth'.ct in intcgra Jiiperficie 40 ferticas. See Perch.
PERVISEor Parvise, a Term in our old Law Books. Fortefaie fays, Plaoitantes {foil foft meridiem) fe divertunt ad pervifum c5 alibi cum fervientibus ad legem c5 aliis. Seidell in his Notes on Fortefme, defines this to be an Afternoon's Exercife, or Moot, which the Pleaders held for the Inttruclion of the younger Students; bearing originally the fame Name with the Parvifia: in Oxford. See Moot.
M. Somner fays, that Pervife fignifies jsalatii Atrium vet area ilia a fronte auU IVeftmouafierienfis, hodie the Palaoe- Xard. See Paradisus.
Sfelman obferves, that the Lawyers turn'd thither to meef their Clients not to hold Moots.
PERVIGILIUM, inMedecine. See Vigilia.
PERUVIAN-Bark. See Cortex Peruvianas.
PES, a long Meafure, in Englijli, better eall'd a Foot. See Foot.
Pes Foreftte. Kotandum eft quod pes foreftai ufitatus tem- pore Ric. Oyfell in Arrcntatione vajJaUorum, jaBns eft, figna- tus & fcufous in fariete Cancellce Bcclefi£ de lidwynftone & in Ecclefia S. Mariie de Nottingham, g? dicJus fes amtinet in hngitudine oilodecini follices, £j in arrentatione quoruw-- dam Vajfalhrum Pertica 20, 21, £s? 24 pedum ufafuit, eVc.
Pes Monetce, in ancient Records, fignifies a true and rea- fonable Adjuftment of the real Value of all current Coin. Soe Standard and Coin.
PESA, an old Law Term, for a Wfey, or certain weight of Cheefe, Wool, ci?c See Wey.
PESADE, in the Manage, that Action taught a Horfe, wherein herifes with his fore Feet, and bends 'em up to his Body, without ftirring the hind Feet.
The Pefade is the firft Leftbn taught a Horfe, in order to bring him to Curvetts, $§c. unleis he perform this well, he'll never go well in any Air, yet is he not to be taught it at the firft Riding.
PESAGE, a Cuftom or Duty paid in certain Markets, %S/C. for weighing of Merchandices, of Wares. See Weigh- ing.
PESSARY, in Medicine, a folid Medicament, of the Length and Thicknefs of the Finger, but a Pyramidal Form ; convey 'd into the natural Parts of a Woman to provoke, or put a Stop to the Menfes, or to prevent a Defcent of the Matrix, or on other Occafions of thofe Parts.
At one End 'tis faften'd to a little Ribbon, by which it may be drawn out at pleafure.
It confifts of Cork, or other light Wood, or of a little Lin- nenBag, full ofPouders, incorporated with Wax, Oil, and Cotton ; cram'd clofe together to make it folid enough for in- tromiflion.
The Word is form'd from Greek trwi;, which fignifies the the fame Thing.
PESTILENCE, in Medicine, a contagious Difeafe, ufual- ly mortal; popularly known under the Name of Plague. See Plague.
The Word is form'd from the Latin Peftis. VzsT-hollfe, a Lazaretto or Infirmary, where Goods, Perfons , i$G. infected, or fufpected to be infected with fome contagious Difeafe, are difpolcd and provided for. See Lazaretto*
PESTILENTIAL Fevers, among Phyficians, are fuch as do not only afflict the Patient with a vehement Heat, but alfo a malignant and venomous Quality. See Fever;
PEST1S. See Plague.
PETALA, in Botany, the Leaves of a Flower; fo eall'd to diftinguifh 'em from the Leaves of the Plant. See Leaf*
By Flower is properly meant, That affemblage of Parts eall'd Stamina and Piflil, which fcrve for propagation of the Kind. See Flower.
The colour'd Leaves which incompafs thofe Parts, are in. reality no more than Cafes or Covers to fecure and fcreen the generative Parts; unlefs, as Mr. Bradley conjectures, they may ferve to fecrete fome fine Juice for the Nourifhment of the Seed. See Generation of Plants.
The moft eafy Divifion of Flowers is into fimple Flowers, /. e. thofe form'd of Stamina and Piftils only ; and compound Flowers, whofe Stainina and Piftils are incompafs'd with <Petala, eall'd by Dr. Grew the Foliation, and by Mr, Ray Folia. See Foliation.
Compound Flowers again, are either incompafs d with a Angle Petalum, or Piece ; or with feveral Pieces ; the firft of which are eall'd Monofretalous, the fecond Polypetalous Flowers. See Monopetalous, f$c.
Again, from the regular or irregular Configuration of the Petala, M. Jllffieu makes another Divifion of Flowers into Clafles; as regular and irregular Menofatalous ; regular and irregular Polyfetalats, gfc See Polypetalous.
Nature fhews a World of Art in the folding up of the Peta-
la, in the Perianthium, before they begin to blow or expand :
Of thefe Foldings Dr. Grew notes the following Varieties,
Ilia, the clofe Couch as in Rofes ; the concave Couch as in
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