f ) 
Antagonlji^ whofe re-afbion ftioud produce it, have beca 
cxcreamly perplext to find out the caufe of it. 
But paffing over the various opinions of Authors, to a- 
void being tedious, I (liall take notice here only of the very 
Learned Dr Lowers, in whofe account of the Sjfiole, how- 
ever folid and ingenious, I obferve fomething deficient, 
and whofe Hypothecs of the Diajiole I think to be precari- 
ous and falfe. 
This excellent Author, having by found Arguments, 
drawn from the Strufture and Mechanifm of the Heart, 
eftablifht the certainty of its Mufcular Motion, refts fatis- 
'fied, without taking notice of any Affiftance, that the Heart 
receives from any other Part, except from the Brain, by 
the means of the eighth Pair of Nerves. 
The Accurate Borellus in his Oecommia Ammdk com- 
putes the Motive Power of the Machine of the Heart to be^''''^ 
equal to, or to furmoont that of a Weight of 3000 /, The^l^^^; 
Objkdes to the Motion of the Blood thro the Arteries he 
efteems equivalent to 180,000/. which is- 60 times as much 
as he rates the Force of the Heart at.Then deducing 45,000 /. 
for the Adventitious Help of the Mufcular Eld(lick Coat of 
the Arteries, he leaves the Heart with a Force of 3,000 /. p^^^ 
to overcome a refiftance of 135,060/. that is, with i to 
remove 45. 
This ftupendous efFed he contents himfelf to afcribe to 
the Energy of Fercujjion, But, had he proceeded in his 
Calculation to the Veins^ which he allows to contain con- 
ftantly a quantity of Blood, quadruple to the Contents of 
the ArterieSj and to which this Energy of Percujjion dees ei- 
ther not reach at all, or but very languidly, he might pro- 
^■bably have feen a neceffity for feme other Expedient to re- 
move fo infuperable a difficulty. 
But not to infift rigoroufly on the exaftnefs of this Cal- 
culation (tho the great Abilities of the Author in this way, 
and his Ingenuity and Modefty, are afufficient Warrant for 
the accuracy of his Computations, and the fidelity of his 
Accounts) we may allow a much greater Dedudion, than 
Cccccccc 2 would 
