5^ ^Joe M of F A R R I E R ^ 



Aarfa or great Artery arifing out of the left Ven- 

 tricle of the Heart. 



There is no Time when all the Blood can be faid 



to have once circulated : But, if there were any fucli 



Time, the Quantity of Blood in the Body mull be 



iirfl determined, which is very difficult to do, and 



not yet fully agreed upon by hardly any two Perfons. 



Bkcling to Bleeding to Death can never give the Eflimate of 



noTeH-eT ^^^ ^^^^ Quantity ; becaufe no Animal can bleed 



tr^ic Eili- lottgt^r than while the great Artery or Aorta is full, 



maie ofthe which will be longer or Ihorter as the wounded Ar- 



Oiantity o' tery is fmaller or greater, and the Jorta mull al- 



Bloocl in 3 }3g t|jg ^^^ -V^m that empties. 



ans Animal, ^, ,, • Txr j i • ^ r j i. ^ 



^ The moil certam VV ay, no doubt, is to find what 



Proportion the Cavities of the Veffels, of which 

 i'mQ whole Body is compofed, bear to the Thicknefs 

 of ,their Coats : And this in the Veins and Arteries 

 may be exactly found, but in the other Veffels, we 

 only know the Quantity of Fluid they contain, by 

 carefully evaporating as much as poffible, which the 

 ingenious Dr. Keil has try'd to a Nicety ; and by 

 his Experiments it is found, that the Liquors con- 

 tained in the Veffels of the Body are ( even at the 

 lowefl Calculation ) one Half of the Weight of the 

 whole Body. And if a Calculation be made on the 

 Proportion of the Blood in the Arteries to their 

 Coat?, in a Body weighing 1 60 Pound, there will 

 be ifound 1 00 Pounds of Blood. I ihall now pro- 

 ceed to a Defcription of that admirable Piece of 

 Mechanifm the Heart. 

 The Peri- In defcribing the Heart, it may be of Ufe to pre- 

 c;irdn m j^jf^ x!ii2X of the Pericardium or Bag in which the 

 uuaib.'d. j^g^j.(. is contain'd, becaufe they have fuch a near 

 Relation to each other. The Pericardium, fo cali'd 

 from-T^epJ, circum^ about, and>t<:t(>J^ii/5 cor, the Heart, 

 is a thin Membrane of a Conic Figure, that re- 

 lembles a Purfe, and contains the Heart in its ■Cavi- 

 ty. ' Its Bafib or Bottom-Part is pierced in five Places 

 hi' ^e Pafxhge of the \'effeb ^^■hich enter and come 



out 



