_Alphonsus Borellus_, after a great deal of solemn pains taken to shew his Care and Exactness, and to possess his Reader of the Truth of his Calculations, casts up the force of the Heart, and the _Muscular_ Coat of the Arteries, to be together equal to a weight of 3,750_l._ and allots them a Resistance equal to 180,000_l._ to overcome which is 45 to 1. To make up for a disproportion, by his own confession, incredible to those who have not consider'd the Matter as he had done, he flings into the Scale the additional _Force of Percussion_, which he leaves _indefinite_, and thinks sufficient to _force any quiescent finite Resistance whatsoever_. But as this Account and _Hypothesis_ are part of a Posthumous Work (if a liberty of Conjecture may be allow'd in so uncertain a Matter,) I shou'd suspect, that these Papers were left unfinish'd by _Borellus_; or at least, that in many places the last Hand was never put to them. For neither in this Place, nor any other of this Work, does he account for any more than the _Systole_ of the Heart, and the resistance which is made to the progressive motion of the Blood in the Arteries only. This alone he found to exceed the Power of the Heart so prodigiously, that he seems to shuffle it off his Hands with a general and precarious Solution, as a difficulty that he was desirous to be rid of. For, having ascrib'd this _stupendous_ (as he himself calls it) effect to the _Energy of Percussion_, he takes no care to satisfie his Reader any farther about it, or to refer him, or give him the expectation of Satisfaction any where else; although he has an express Treatise on the _Force of Percussion_, which was written preparatory to this, and to which he frequently refers in other Places of this Work. But what confirms my suspicion, that this part was intended for a farther Revise by the Author, is, that he has left the Progress of the Blood through the Veins, and the _Diastole_ of the Heart, absolutely untouch'd, tho' they are Difficulties of a much greater magnitude than this, which he has attempted to account so slightly for: For, in these he is excluded the benefit of _Percussion_, and has yet a greater resistance to overcome without it. Omissions of this kind are so unusual with this Author, where-ever he knows himself to go upon sure grounds, that it is to me an Argument, that he doubted the sufficience of his _Percussion_, and reserv'd these important _Phænomena_ for farther Consideration, without plunging himself into such an Absurdity, as to ascribe to _Percussion_ any such _Energy_ as to be able (so broken as it returns to the Heart) by its re-action to force that Power, from whence only it was at first deriv'd.