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.
Dr. Lower, and Mr. Cowper, deliver their Opinions of the Cause of the Dilatation of the Heart so very