Page:Cyclopaedia, Chambers - Volume 1.djvu/379

 C I R

The molt fubtil Parts of the Arterial Blood being car ry'd from the Heart to the Brain by the Carotid Arteries

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C I R

are thrown violently into the fine Network, wherewith the Bottom of the Ventricles of the Brain is lin'd ; whence the more delicate Parts are driven into the Months of the Cho- roid Arteries, where they continue their rapid Motion, and dilcharge themfelves at the Pores where thofe Veffcls termi- nate around the Pineal Gland.

Hence they enter that Gland, and there form a conftant Spring of Spirits; which being here purify 'd, enters the Ca- vities of the Brain, and infinuating into the Pores of its Subftance, flow into the Lymphatics ; whence they are car- ry 'd to the Heart by two ways.

Thofe from the upper Parts by the Subclavian Veins, and the adjacent Veffels : thofe from the lower, beinn difcharg'd into <Pccquet's Refervoir, proceed by the Thoracic DiTft and at lalt by the defcending Veins to the Heart. Whence' they begin tneir Courfe afrefti.

Circulation of the Sap, is a natural Motion of the nu- tritious Juice of Plants, from the Root to the extreme Parts, and thence back again to the Root. See Sap, and Plant! The Experiments of modern Naturalifts, and Gardeners fcem to prove a Circulation in the Body of Plants, by Veins and Arteries, analogous to that in Animals.

M. Terrault firit ftarted the Circulation of the Sap in France and propos'd it, in itS6y, to the Royal Academy : Tho M. Major, a Phyfician of Hambourg, had publifh'd it unknown to M. Terrault, two Years before. A Year and half afterwards, M. Mamotte propos'd the fame to the Aca- demy as a new thing ; not knowing that M. <Perrault had been beforehand with him : And the great Malpkbi appears to have entertain'd the fame Thought about the lame time.

The Opinion, however, is not univerfally teceiv'd : Tome or the ablcft Botanitts, and particularly M. Dodart proteft- mg openly againlt it.

That Author allows of a Juice mounting from the Root to the Extremities of the Branches ; and of another de- icending from thefe Extremities to the Root : the firit im- bibd from the Soil, and digefted in the Root, for the Npuriilvment of the Plant : the fecond received from the moift Parts of the Air, in at the Extremities of the Bran- ches. The nfing and defcending Juices, therefore, accord- ing to him, are not the fame; or, that which rifes never de.ccnds, and reciprocally ; /. e. there is no Circulation.

Dr Jjjj in the Tbilofipbical tranfa£lims, maintains, that the Sap always rifes, and never properly defcends ■ hav- ing only a Subfiding, or Recidivation, which he can by no means call a Circulation.

in a Circulation mould be effefled ; as well as for the Pa- rity of Realon commonly urg'd for a Circulation of the Sap and of the Blood In Animals, he obferves, the degree of Growth, or Extenfion, is but very fmall : fo that the Blood not being employ 'd in any other fetvice, may be eafily fup- pos d to circulate : But Trees, growing to an unlimited Tall- nels, tis probable the great Effort of Nature is employ'd in extending cm that way ; and that the nutritious Juice only afcends. He adds, that as to the Swelling or Extenfion of Trees in bulk, it evidently arifes from the Effufion of the Sap from the Heart of the Tree thro' the Pores, which di- lates the whole lhfenfibly, by accumulating Circle on Circle ■ which are annual Gradations eafily obfeiv'd upon cutting a Branch, or Trunk acrofs.
 * U.Szvitzer owns himfelf at a Lofs for the Method where-

But flill, the Arguments for a Circulation, mult be allow'd of more weight than any thing here urg'd againlt it.

The fame Experiments of Ligature, and Incifion, which evince a Circulation in Animals, have been made in Plants • particularly in fuel, as abound in Sap, as theMilk-Thiflle iSc and with the fame Succefs ; the Part between the Ligature and the Root fwelling very confiderably, and the other much lefs.

The Ligatures are to be made with metalline Rings. Dr. Ziftergivts us an Inftance in the Catafutia minor, where the Ligature being only a filken Threadf ty'd as hard as poffible without breaking the Skin, no greater Swelling arole on one fide the Ligature than the oth?r

Mr. Lawrence gives us a Dcmonflration of the Circulation W the Sap, from an Experiment on the yellow ftrip'd Jef-

Upon a Branch of a plain Jeffamine, whofe Stem fpreads t Id in two or three Branches, inoculate a Bud of the yel- low ftripd Jeffamine, in Autumn : As the Tree comes to inoot, the t fonowing Summer, fome of the Leaves will be tound tmgd here and there with yellow, and this even on the Branches not inoculated ; till, by degrees, the whole lree, even the very Wood of tho young Branches, will be all variegated, or ftrip'd with green and fellow. See Varie-

GATION. '

Mr. Fairchjid confirms this Experiment by a fimilar one ot his own : Having inoculated a yellow fpotted Jeffamine Tree, into another Jeffamine Tree ; he found, that tho the

Bough did not take, yet in 1 Bo»Bi.kJ .• begin ,0 appear on a'shoot which fmVout^f \f°C ^ from another Part of the Plant. See M UL e ""^

As to the manner of the Circulation-, it is not di'ffi,-,... . conceive. Malpigbi, Grew, &c. by mean, of Mi r havedifcover'd, fhat the Wood of IC/c nfiftf t^C? pillary Tubes, which run parallel from the Root! tW the

fid, f' w T y bC l0 ° L k ' d °" iS A " cri « \ «>d ™th™ out- fide of thefe, betwixt the Wood and the inner Bark, are o- ther large Tubes, to do the Office of Veinj

EanWh^T 1100 ' h !, V L ng imbib ' d a Stock of M<* &om the it w il'h J f m W1 " J be Pf in motion b y the Heat; that is, VaTou ■ M yd ' and ™ de t0arcend in fotm °f» S'eam or the P Ar eriafv 7,' $*&*,*¥> thc P at ™ M °"ths of ^S,P*A"!^ thro' the Yame to the Top theH c " t C b v e ^ rt r ft - heTree > With a Fotceanfwerable «S tne neat by which it is put in motion : when it is there nr,

de V n d s'd rnto e " n L W " h *° W- f th ° « *k, his co - clensd into a Liquor; and in that form returns by its own weight, towards the Root of the venal Veffels aUemL

the C fame v7™ N ' in S b 7 mifl ty. >> *" Operation whereby

and d i,liy P i r r ' T Sd byKre ' fclls back i ro be return'd

fubtil Yt 1 t'n " m "' and thlls «<•«« d int ° its W0ft lubtu fans. See Distillation

Vefflriffn'J SI,erfbl ' m ' dbydir P°' ;!1 g theLi u"'>tin a fingle Veil c7lt " ? P ' Ca o"' d a ' Peltcm i « in a doufle ilwer'toro t^l T FKCeS > lllKd ™each other; the bwer to contamthe Liquor. See Prl.can, and Dooble

Afi3s S P e r rf °™' d 5 ither ty the Heat of a Lamp, or that of Sun if Jut? i m0deratd y h °t, or in Dung, or by the Sun. It ufually demands a continued heat of flveral Days, fometimes of liveral Weeks, or even feveral Months. See Fire, and Heat.

By Circulation, the fined Part of the Fluid mounts to the Top of the Veffel ; an d finding no iffue there, falls back again, and rejoins the Matter left behind at the Bottom, whence it arofe : and thus, by continuing to rife, and fal alternately m the Veffel, there is effected a kind S emu- lation, or Remixt.on of the fpirituous Pans with the grofs ones ; whereby the former are render'd finer and more fub- til, and better difpos'd to exert their Activity when fepa- rated from the latter. Sec Rectification

, v C 'f C v^- A, T ? RY ' CIRCULATORIUM, in Chvmif- try the Veffel wherein a Fluid is put, to undergo the Procefs at Circulation. See Circulation ,, ^"e are two Kinds of Circulatories, the Ttiota, or dou-

e nSttf,c he? o ta

URCULUS, in Geometry Logick, (ge. See Circle.

_ Circulus among Chymifts, is a round Iron Inftrument, us'd

in cutting off the Necks of glafs Veffels : which they effefl

tnus. '

The Inftrument being heated, is apply'd to the glafs Vef- fel, and there kept till it grow hot : then, by a few Drops of cold Water, or a cold Blatt thereon, it flies afunder.

Thus they cut off the Necks of Retorts or Cucurbits. See Retort, (gc.

_ There- is another Method of doing the fame, viz. by ty- ing a Thread firit dipp'd in Oil of Turpentine, round the

fheThreaT '" '" bC ' ™ d thc " kt " 1 ^ fire to

,n JrLr m % f u me co ! d W, at « being fprinkled on the Place, the Glafs will be crack'd thro' precil'ely where the Thread Wets ty o»

Bn ^RCUMAGENTES Mufculi, in Anatomy. See O-

CIRCUMAMBIENT, an Epithet denoting a thing to in- veft or incompals another around. See Ambient

^e '*y the Jmiient, or Circumambient Ah,&c. SeeA IR Atmosphere, gfc '

CIRCUMCISION, the Afl of cutting off the Prepuce : or a Ceremony ,n the Jeiv.Jl, and Mahometan Relioions, wherein they cut away the  that fuffm V r? e A PP oi "tment, circumcis'd himfelf, and t 1 1 ^ v° f i" s Fami 'y 5 from which time it became an hereditary Praftice among his Defccndants.

ine Ceremony, however, was not confin'd to the 7ews : Herodotus and "Pbilo Judmis obferve, that it obtain'd alfo among the Egyptians and Ethiopians. Herodotus fays, that the ^ultom was very antient among each People ; fo that there was no determining which of them borrow'd it from the other. The fame Hiftorian relates, that the Inhabi- tants of the Colchide alfo us'd Circumcifion ; whence he con-

r iiHf.p A...-1 - ■ 11 -^,. ■ . xt ..

-, — l "^- ^uicvute ano us a 1,/rcumcuion ; wnence he con- ehides, that they were originally Egyptians. He adds, that the J^banicians and Syrians were like wife circumcis'd ■ but that they borrow'd the Praflice from the Egyptians. And laftly N n n tha r