Page:Cyclopaedia, Chambers - Volume 2.djvu/532

 P U L ( pop ) P u M

fiend the fides of the Artery ; and thus is a Motion ofDi- Or, laftlv, to an jSPbhvxU „,h -. latation effected. Ii* j..i.-.,m J

And when the Impetus of the Blood againft the fides of the Artery ceafes, that is, when the left Ventricle ceafes to contract, then the fpiral Fibres of the Artery, by their na- tural Elafticity, return again to their former State, and con- tract the Channel of the Artery, till it is again dilated by the Syftole of the Heart ; fo that here is a Motion of Refti- tution effected.

ThisDiaftoleof the Artery is call'd its Tulfe, and the time of the fpiral Fibres returning to their natural ftate, is the diftance between two Pulfes.

This Tulfe is in all the Arteries of the Body at the fame time : fot while the Blood is rhruft out of the Heart into the Artery ; the Artery being full, the Blood muft be pro- pell'd in all the Arteries at the fame time ; and becaufe the Arteries are conical, and the Blood moves from the Balis of the Cone to the Apex, therefore the Blood is con- tinually prcffing againft the Sides of the Veffels, and confe- quently every Point of the Artery muft be dilated at the fame time that the Blood is thrown out of the left Ventricle of the Heart ; and as foon as the Elafticity of the fpiral Fibres can overcome the Impetus of the Blood, the Arteries are 3gain contracted.

Thus, two Caufes operating alternately ; the Heart, and Fibres of the Arteries, keep the Blood in a continual Mo- tion. See Circulation.

The Oblet vation of the Tulfe a of the laft Importance to aPhyfician; both as it difcovers the State of the Heart, the firlt Mover in the Animal Frame; and as it ihews the Mature, Quantity, and Motion of the Blood, that univerfal Humour whereon all the reft depend ; and as it indicates the condition of the Artery, the primary Veffel of the whole Body.

opting Tulfe, then, denotes, r. A great Mufcular Force of the contracting Heart ; and, confequently, the ftrength of the contracting Caufe ; i. e. 2. A brisk and copious In- flux of the nervous Juice into the Villi of the Heart.

3. Plenty of Blood. 4. A laudable Secretion and Circula- tion of Humours.

A ftrong Tulfe, therefore, is a good Prefage, if it be alike throughout the whole Body. Indeed it is frequently falla- cious in Apoplect ic, and fome other Difeafes ; where the Paffage between the Heart and the Brain is free ; and in other parts, efpecially the Vifceta, obstructed.

A weak Tufe denotes the contrary of the former ; tho this lome mes deceives, particularly in fat People.

A hard Tulfe fignifies, 1. That the Membtane of the Artery is dryer than ordinary : And, therefore, 2. Ob- foucfions in the minute Veficles whereof the Membranes of the Artery are wove. 3. That the Arteries are full ; but,

4. That their Capillary Extremities are obftrufted with an inflammatory Vifcidity. 5. That the Blood is very denfe and compact : Hence, 6. That the Circulations, Secre- tions, f.nd Excretions are depraved.

A fift Tulfe denotes the contrary to all thefe ; yet is very fallacious in an acute Teripneumonia.

A flow Tulfe denotes, 1. That the Contraaions of the Heurtare flow ; and, therefore, 2. A Slownefs of the In- fluxes of the nervous Juice from the Brain into the Villi of the Heart. 3. That the Blood has circulated a great number of Times. 4. That all the Humours circulate eafily thro' their Veffels. Indeed if the Pulfe be thus from WiakncO,, 'tis an ill fign.

A quick Tulfe denotes the contrary to all thefe ; as Acri- moues, Spirits agitated, Fevers, Phrenzy.

An equable Tulfe denotes a conftant Tenor of the vital Funcli- ns ; an unever ore the contrary.

An intermitting Tulfe (hews Life in a flippery Situation.

An intermitting Tulfe is either owing to a fault in the nervous Juice, which flows unequally into the Heart j or in the Veffel which tranfmits the Blood and Humours ; or to the Humours themfelves.

The Caufe of this Diforder is various, as Convulfions, Polypus's, Cacochymias, Inflammations, want of Blood, bony or cartilaginous Arteries, cifc.

A ftrong, equable, and, at the fame time, flow Pulfe, is of all others the beft. A ftrong and great ; or ftrong and flow Tulfe, together, are good. A weak, fmall, hard, un- equal, intermitting, quickTulJe, is of all others the worft.

Yet in all thefe things, regard muft be had to the nature of of Titmice in Medicine the particular Artery, the Age, Sex, Temperament, Affections Practice, of tho Mind, the fix Non-naturals, Habit of Body, Seafon, Country, Sfft:. All which have an influence on the Tulfe.

> A Diminution or total Sufpenfion of theTulfe, is redu- cible, f either to a Leipothymia, where it fails to fuch de- gree, as that there is Icarce ftrength left to fuftain the Body. See Leipothymia.

Or to a Leipopfychia, when it arifes to a fenfible Dimi- nution of the natural Heat.

Or to a Syncope, when the Heart fails, fo as the Heat, Motion, Senfes and all are almoft deflroy'd.

v.^re thofe are all abio lately de.troy d as to oenle, and Death itfelf items in pof- (eflion. See Syncpe, JiJC.

• V £ " E " r °, ufe <J for "» S.roke.with which any Mcdiim is affefted by the Motion of Light, Sound, iSc. through it. See Light and Soon d.

Sir Ifaao Newton demonftrates, lib.*, Tnp.tfi Vrincip. That the Velocities of the Tnlfes w an Elaine Fluid Me- dium, (whofe Elafticity is proportionable to its Denfity) are in a Ratio compounded of half the Ratio 0/ the Elaftis Force directly, and naif the Ratio of the Denfitv invcrfely : So that in a Medium whofe Ehilicity is equal tojts Denfity all Tuljes will be equally fwift. See Medium, Fluid* 55 c.

Pulse, Legumen,\n Botany, a Term ufed for thofe Grains or Seeds which are gather'd with the Hand 5 in contra- distinction to Corns, i£c. which are reap'd, or mow'd.

Tulfe is the Seed of the leguminous Species of Plants. See Leguminous.

The Word is primarily undcrftood of Grains that grow in Pods ; as Beans, Peas, Vetches, IvC. but is alfo ufed, by Extenfion, for Artichoaks, Afparagus, and other Kitchin- Roots and Herbs.

PULSION, orTrufiou, the A3 of driving, or impelling a thing forwards. SeeTltusioN.

The Word comes from pello, I drive. See Attrac- tion and Electricity.

PULTURA, in our old Law-Kooks, denotes a previous Examination ; from pufare, to ask, or demand, thus call'd on account of the Monks, who, e'er they were ad- mitted into the Monafteries puifabant tld fores, for feveral

days. Et -job tit pit quieti de omnibus Caiifis (S gtie-

relis, (SiplacitisBaUivorum EjJ Trtpofitomm Unndrcdt, ($ a Pultura Serjanorum ; i.e. from the Examination of Ser- jeants ; iSde rewardo Foreflaritm, 2. e. th; Vifitation of the Foreft.

PULVERIZATION, the Afl of Pulverizing, or redu- cing a Body into a fine Powder. See Powder.

This is performed, in friable bodies,, by pounding or beating in a Mortar ; but xo pulvcriz-e malleable ones, other Methods muft betaken. See triable and Malleable.

Topulverize Lead, or Tin, the Method is thus : Rub a round wooden Box, all over the inlide, with Chalk ; pour a little of the melted Metal nimbly into the Box, when, /hutting the Lid, and (baking the Box briskly, the Metal will be reduced into Powder. See Trituration.

PULVINATA, Pulvinated, in the antient Archi- tecture, a Term apply'd to a Freeze which fwells, or bulges out, in manner of a Pillow ; whence the ISame. See Freeze.

PULV1S Fulminttns, or the thundering Powder; fee

FuLMINANS TlliviS.

Pulv is Tatrum, the Jefuits Powder ; fee Cortex and Quinaojjina.

PUMICE Stone, Pumex, a kind of fpongeous Stone, very porous and friable. SeeSToNE.

Naturalifts are not agreed about the Nature and Origin ofTumice — Some look on it as pieces of Rock half-burnt and calcined, caft up in Eruptions of Volcano's, particularly AUnamd Veflivius, into the Sea ; and which, by being there walfi'd in theSah-water, lays afide the black Colour that the Impreflion of the fubterrancan Fires had given it, and becomes whitiifi, or fometimes only greyifh, according as it ha* floated more or lefs in the Sea.

Other Authors will have xheTumice to rife from the bottom of the Sea j whence they fuppofe it detach'd by fubterranean Fires, and hence account both for its lightnefs and porofity, and its faline Tarte. Alledging, in con- firmation hereof, that Titmice is frequently found in parts of the Sea far remote from all Volcano's ; and adding, that feveral parts of the Archipelago are frequently found co- ver'd with it, all at once, after a few inward (hakes and heavings of the bottom of the Sea.

Tumice makes a very confiderable Article in Commerce, and is much ufed in the Arts and Manufactures to polifh and fmooth feveral Works. See Polishing, i£c.

Its pieces are of feveral Sizes : The Parchment-Makers and Marblers ufe the largeft and lighteft. — The Curriers theheavieft and flatteft. — Pewterers rhefmalleft.

Pliny obferves, that the Antients made confiderable ufe but it is out of the prefent

PUMP, Antlia,\x\ Hydraulics, a Machine form'd on the Model of the Syringe, for the railing of Water. See Syringe.

Vitruvius afcribes the firft Invention of Tumps to Ctefebes the Athenian, whence the Latins call it Machina Ctefe- biana, or Organum Ctefebicum.

TumpSixft diftinguifti'd into feveral Kinds, with regard to the feveral Manners of their acling — As the Common, fometimes call'd the Sticking- Tamp, which a£ls by the preffureof the Air, and whereby Water is raifed out of a lower into a higher Place not exceeding thirty-two Feet : ic X The