Page:Cyclopaedia, Chambers - Volume 2.djvu/531

 PUL

( 5>q8 )

PUL

Olearius, who was at Jfcahan in i6y,, in the Retinue of the Ambarfador of Holftein, affures us, That each City in 'Perjia has its feveral Copper-Money, mark'd with its par- ticular Badge, which is only current in that Diflrict, and changed every Year. — At the beginning of each Year, which is at the Vernal Equinox, all the old Money is cried down, and the new appears in its place. ,

Both the Emperor and the State find their Intereft in this frequent change : The firit, in that he only gives at the Rate of 17 d. Sterling /«- Pound for Copper ; yet delivers it out coin'd in Kabefqui and 'Memi -kabefqui at above is. per Found : The fecund, in that the Copper-Money is by this Means lcfs abundant, being reduced each Year to nearly the fame Quantity. , ,

The fame Author adds, that at the Time when he was in Perfia, the Kabefqui at Ifpahan were flruck with the Image of a Lion, at Scamachia with a Devil, at Kafchau with a Cock, and at Kilan with a Fifli.

PULLEY, trochlea, in Mechanics, one ot the five Me- chanical Powers ; confilling of a little Wheel, or Rundle, having a Channel around it, and turning on an Axis ; ferving, by means of a Rope which Hides in its Channel, for the railing of Weights. See Mechanical Tower.

The Latins call it Trochlea ; and the Seamen, when fitted with a Rope, a Tackle. — An Affcmblage of feveral Pulleys is call'd a Tolyfpafhm,

Tioclrine of the Policy:.

i°. IfaPowerP, (Tab. Mechanics, fig.49.) Main a Weight Qj by means of a fingle Pulley A B ; in fuch man- ner as that the Line of Direction of each is a Tangent to the Periphery of the Bundles the Weight and the Power are equal.

Hence, a fingle 'Pulley, if the Lines of Direction of the Power and the Weight be Tangents to the Periphery,

neither affiils nor impedes the Puwer ; but only changes its grows and fwells by means of a Juice, at fir It very coarfe Direction. and difagreeable ; at length Tweeter and more delicate.

The L'fe of the Pulley, therefore, is when the vertical Sec Parenchyma ; feealfo Veo etable, Plant, tic. Direction of a Power is to be changed into an horizontal Pulp, in Medicine, the fattefl, fuller!, and moll iolid one ; or an afcending Direction into a defending one ; and part of the Flefh. See Flesh. on the contrary. Phyficians apply the Word particularly to the upper part

This is found a good Provifion for the fafety of the Work- of the Belly; becaufe flefhy, and becaufe 'lis hete that menemploy'd in drawing with the Pulley. — For fuppofe a they feel Animals, to examine whether they be fat. large Weight E Fg requir'd to be raifed to a great Height _ This part the Latins call Pulpa, from palpare, to feel,

Pulmo Marinus, Sea-Lungs, among Naturalift S] a light fpongeous Body, of a fliining Colour, like Cryflal, in- termixed with blue, and ufually of a Figure refembling the human Lungs 5 whence its Name.

It fwims a-top of the Water ; and is popularly fuppofed to prefagea Storm.— It is in effect no more than a vifcous Excrement of the Sea, hardned by the Sun.

It mines in the Night-time, and communicates its lumi- nous Property to a Stick rubb d therewith. Being apply'd to the Skin, it raifes an Itching, and takes off the Hair.

PULMONARY Veffels, in Anatomy, are thofe which carry the Blood from the Heart to the Lungs, and back again from the Lungs to the Heart.

Thefe are two in Number ; via. the Pulmonary Artery and Vein.

The Pulmonary Artery, which the Antients call'd Vena Arteriofa, the Arterial Vein, is, in reality, an Artery, and compofed, like the reft, of feveral Tunics.— It arifes from the right Ventricle of the Heart, and divides into two large Branches, which fub-dividing into feveral fmaller, diffufes itfelf throughout the whole Subltance of the Lungs. See Lungs.

The Pulmonary Vein, which the Antients call'd Arteria Venofa, the Venous Artery, confifts of four Membranes like the other Veins. It atifes in the Lungs from an infinity of little Branches, which uniting in one Trunk, opens into the left Ventricle of the Heart. See Heart.

For the Office of thefe Veffels, fee Circulation. Sea alfo Respiration, ££c.

Mr. Confer gives us an Inftance of a Polypus in the Pul- monary Vein. See Polypus.

Pulmonary Confumpticn, orConfumption of the Lungs, is what we properly call a Ththifis. See Phthisis.

PULP, in Fruits, the Flep ; or that part between the Skin, and the Core, or Seed. See Fruit.

The Pulp of a Tree, or Plant, is the Parenchyma, which

by Workmen pulling a'Rope A B: If now the Rope (hould chance to break, the Workmen's Heads underneath would be in immediate Danger ; but if by means of the Pulley B, the vertical Direction A B be changed into a horizontal one B C, there is no danger from a breaking of the Rope.

This Change of Direaion by means of a Pulley has this further Advantage ; that if any Power can exert more Force in cne Direction than another ; we are here able to employ it in its greateft force.

Thus, e. gr. a Horfe cannot draw in a vertical Direction ; but draws with all its Advantage in a horizontal one. By changing the Vertical Draught, therefore, into a horizontal one, a Horfe becomes qualify'd toraifea Weight.

i". If a Power apply'd in E, {Fig. 50.) according to the Line of Direction B E, which is a Tangent to the Pulley in E and parallel to the Rope A D, fuftain the Weight F fufpended from the Centre of the Pulley C ; the Power is fubduple of the W'eight.

But the gtand Ufe of the Pulley, is where feveral of 'em are combined ; thus forming what Vitruviiis, and others after him, call Polyfpajla ; the Advantages whereof are, thar the Machine takes up but little room, is eafily re- moved, and raifes a very great Weight with a very mode- rate Force.

The effect of Polyfpajla is founded on the following Theorem.

3 . If a Power apply'd in B, (Fig. 51.) fuftain (by means of a Polyfpaflon) a Weight F, fo as all the Ropes A B, H I, G F, EL, CD, are parallel to each other : The Power will be to rhe Weight as Unity to the Number of Ropes, H I, G F, E L, C D, drawn by the Weight F ; and therefore as Unity to the Number of Pulleys, higher and lower, taken together.

Hence, the Number of Pulleys and the Power being given, 'tiseafy to find the Weight that will be fuftain'd thereby: Or, the Number of Pulleys and Weight to be fuflain'd, being given, the Power is found : Or, the Weight and Power being given, the Number of Pulleys the Po- lyfpaflon isto coniift of, is found. See Polyspaston.

4°. If a Power move a Weight by means of feveral Pul- leys ; the Space pafs'd over by the Power will be to the Space pafs'd over by the Weight, as the Weight to the Power.

Hence, the fmaller the Force that fuftains a Weight by means of Pulleys, is ; the flower is the Weight raifed : So that what is faved in Force, is fpent in Time.

PULMO, in Anatomy, fee Lungs.

handle.

Pulp, in Pharmacy, is the foft part of Fruits, Roots, or other Bodies, exttacted by infufion, or boiling, and paffed thro' a Sieve.

PULPIT, Pulpitum, a Term now reftrain'd to an Ele- vation, or Apartment in a Church, whence Sermons ara deliver 'd.

Among the Romans, thePulpit was apart of the Theatre, call'd alfo Profcenium ; or what we now call the Stage, whereon the Actors trod ; tho' fome fay it was properly an Eminence thereon for the Mufic, or a Sllggeflum whence Declamations, i£c. were fpoke.

The Frencbukthe Word Pulpit, Pupitre, fora Reading- Desk in a Church, Library, or the like : Thofe large ones in Churches, they properly call Lutrins.

Some Authors derive the Word from Publicum, becaufe People are there expofed to open view.

PULSATION, in Medicine, the Motion of the Pulfe 5 or the Beating of the Artery. See Pulse.

PULSE, in the Animal Oeconomy, the beating, or throb- bing of the Arteries. See Artery.

ThePulfe is that reciprocal Motion of the Heart and Ar- teries, whereby the warm Blood thrown out of the left Ven- tticleofthe Heart, is fo impell'd into the Arteries to be by them difttibuted throughout the Body, as to be perceivable by the Finger. See Blood.

The Puliation of the Arteries arifes from that of the Heart ; and has, like it, a Syftole and Diattole ; the Syftole of the one correfponcing to the Diattole of the other. See Heart, Systole, &c.

GaUn tells us, that Hippocrates was the firit who ob- ferved rhe Motion of the Pulfe. M. Homlerg mentions the Cafe of a Woman in Paris who had a Pulfe in the Veins, perfectly like that we commonly obferve in the Arteries. He adds, that he is the firit Author that ever mention'd fuchathing. See Vein.

The Pulfe is thus accounted for. When the left Ven- tricle of the Heart contracts, and throws its Blood into the great Artery; the Blood in that Artery, is not only thruft forward towards the Extremities, but the Channel of the Artery is likewife dilated ; becaufe Fluids, when theyare prefs'd, prefs again towatds all fides, and their preffiire is always perpendicular to the fides of the containing Veffels: but the Coats of the Artery by any fmall Impetus may be difiended; therefore, upon the Contraction of the Heart, the Blood from the left Ventricle will not only prefs the Blood in the Artery forwards, but both together will di- tto,]