jS ne Art of Farriery 



the Heart more thau once in their going from, and 



returning to the Bafis. And from hence it appears^ 



that a much greater Number of Fibres involve the 



Left Ventricle tLm do the Right, feeing the Blood 



is by the Right Ventricle thruft only through the 



^ Lungs, but by the Left through all the Parts of the 



Body, even to the Extremities and back again ; for 



it is by the force of the left Ventricle, that the 



Blood returns to the Heart by the Vena Cwva Afcen- 



dens and Defcendens: And that the Force or Con- 



tra£lion of this Ventricle miglit be every where 



Urong, and the Texture of the Heart firmer, thefe 



Fibres are not all parallel, or they do not run all 



witTi the fame Obliquity ; but the inner always de- 



CuiTate or crofs the outer, and frequently mix with 



one another. The Bone which is found in the 



Balis of the Heart of feveral Beafts, particularly 



the Stag, is nothing but the Tendons of the Fibres 



The Fibres ^f ^y^^ Heart offified j and this Bone (as it is felfely 



Hearl ofTifi- ^^^^^) ^^ fo'-^nd in Men. The Heart, which is 



ed in feve- properly called a Mufcle, has two Motions, ^ciz^ 



rt\ Ani- Syjiole or Contraction, and the Diafiole or Dilata- 



^^^' tion. In the firft of thefe Motions, when the 



Fibres contradl, its Sides fwell, and its Cavities or 



Ventricles are lirongly prefs'd from all Parts. The 



Diaflole is when it ceafe^h to a6l ; its Fibres are 



lengthed, its Sides fall, and its Cavities become laige 



and wide. 



The Force by which this Mufcle throws the 

 Blood cut of its Ventricles, or by which it con- 

 trails in its Syllole, has employed the Enquiries- 

 of many in vain : And even the famous Borelli, 

 with a great deal of Geometry to his Affiflance, 

 feems to have been far wide of Truth,, in his cal- 

 culating this Power in the Heart of a human Body. 

 And as the Creature I am treating of has a Heart 

 which, in Contra<^icn, throws out four Times 

 as much Blood as a Man*s ; therefore it muft afl 

 with four Times the Force. I fay Borelli'*s Miftakes 

 proceed moftly from his Reafoning upon improper 



Poftulates^ 



