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the Pipe compressed by the outward Air ; the Force of the Steam would drive part of the Fluid beyond the Valve at the Bend, and its force would cease, and it waste there, and the Compressure upon the returned Part of the Pipe, would force Part of the Fluid through the Valve at the End of the Pipe, into the Part of the Pipe between the two first Valves, where it would find a sort of a Vacuum, or less Resistance, during the first Part of the Second of Time, after the Steam had palsed the Valves, and before it had Time to be issued in sufficient Quantity to open the first Valve, and resist it: and that Vacuum would be somewhat enlarged by the Cold in the returning Auid, which would condense the Steam it should find there, and at the End of the Second of Time, the Steam would push through the first Valve, and Part of the Fluid, and itself, through the next two Valves, and beyond the Bend, so successively. If the Steam were not secreted out of the Pipe by Pores or some other Way, as ’tis out of Animals by their Lungs, Pores, Ureters, &c. the Steam would encreafe the Fluid, fill the Pipe, and hinder theCirculation.

C H A P.

Concern.

C H A P. VI. Concern. The Agents afhgned, which circulate the ing the Blood, secrete the Juices, perspire and

respire the Halitus, Sweat, &c. with the Reasons for assigning them, confirmed by Observations, Reflections and Deo ductions.

Agents.

T HAT the Blood in Animals cir

l culates, and along with it, what enters into it, through the lacteal Vessels, till Part thereof be respired, perspired, fecreted by Urine, and Part be converted into Blood, Flesh, Bones, &c. is now taken for granted. That it requires a very great Force to circulate it, is demonstrable. That several, who have attempted to shew what circulates it, have ascribed Powers or Faculties to Parts of our Bodies which they have not, and Actions which they are not capable of performing, few People doubt. That our Growth, Life, and Action depend upon that Circulation, or upon something secreted out of the Blood by that Circulation, and that most of our Disorders are occasioned by, and attended with unequal,

and

and disorderly Circulation, is very certain. That till the Cause of this Circulation be of Disorknown, 'tis likely the Remedies will be ders. uncertain ; and though I profess no Knowledge in Physick or Anatomy, I have em ployed fome Thoughts about natural and mechanical Operations, and the allowed Apology (for the Good of Mankind) will excuse me for offering my Thoughts upon this nice Subject, tho they be not altogether right.

That which is called the Circulation of Of the Cir the Blood, I take to be two contrary Mo-culatiou of

Drood, tlak DeWo Contal y EU che Blood tions, one going from the Heart along the and the Arteries to the extreme Parts of the Lungs,.Causes of Externals, and Intestines, and the other". returning through the Veins to the Heart, Which two Motions, I think, are performed by two different Agents, the one within the Body, and the other without the Body.

The first, I think, is performed by the The firl Steam raised out of the Meat, Drink, and Agent af.

figned, Juices in the Stomach and Guts; which, which as it rarifies and expands, issues by the drives the joint force of the Pressure of the Atmo- The Heart fphere, and its own Expansion, from thechro' all Stomach and all Parts of the Guts, thro’the Body. the lacteal Vessels into the Receptaculum Chyli, and thence through the Chyle Duct VOL. X.

into

into the * upper Part of the Vena Cava, and so forward through the right Ventricle of the Heart, thence into the Lungs, where the Superfluity of it is difcharged, thence through the left Ventricle of the Heart, thence into the great Artery, thence into the lefser Arteries, to the extreme Parts of the Body, and of the Parts which serve for Secretion or · Discharge, where the Remainder of the

faid Steam condenses or perspires. The se. The second (I think) is performed by cond A-, the Pressure of the Atmosphere, which gent which in the Bind 1 forces the Blood up th

+

he smaller Veins, to the into the upper and lower Parts of the Vena

ohrom Cava, to the Place where they unite, at Body. the right Auricle of the Heart, where the

reti

Steam issued at the inofculation of the Chyle Duct, into the Subclavian Vein, which is at the upper Part of the Vena

Cava near the Heart, takes it. The Use The Heart, I think, uses not, nor has of the Heart.

any great Force to push the Blood forward, but is placed for a Check or Stop: The right Auricle and Ventricle to the Steam and Blood, issued from the Vena Cava, and the left to the Blood, and Remainder of the Steam issued from the

Veins

* Or thus, Into the fubclavian Vein, and so to the right Aaricle, hence thro' the right Ventricle, into the Lungs.

Veins in the Lungs. And its Valves are so contrived; those, from the Veins to open inward; and those, into the Arteries, to open outward, and shut the contrary Way: That as the Mixture of Steam and Blood presses out of the Veins; * it opens the Valves into each Ventricle, fills the Ventricles, extends them, opens the Valves into the Arteries, and pushes forward, whereby the Force of the Steam behind is spent, fo that the Valves from the Veins shut, and the Motion of the Blood in the Ventricles is continued forward, and the Heart emptied jointly by the Elasticity of the Steam, the Compresfion of the Atmosphere, and the Contraction of the Muscles of the Heart; and so fucceffively make a sort of Space or Vacuum, in each Ventricle, at once for the Blood to flow from the Veins, and the Steam from the Guts, * And it seems, that the Strength of the Steam in its

D a

common

• Thro' the Auricles, it opens the Valves into each Ventricle, fills and extends them, and pushes !orward thro" the Valves of the great Artery, and thus the Blood is brought to the Heart; and it is emptied jointly by the E. lasticity of the Steam, the Compression of the Atmofphere, and the Contraction of its own muscular Fibres ; and so by a continual Evacuation of the Ventricles, a Sort of Va. cuum or Space is found for the succeeding Blood and Steam, ready to pour itself in at the right Auricle from the Vera Cava, the Resistance before it being removed.

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