The Accurate Borellus, in his Oeconomia Animalis, computes the Motive Power of the Machine of the Heart to be equal to, or to surmount that of a Weight of 3000l. The Obstacles to the Motion of the Blood thro' the Arteries he esteems equivalent to 180,000l. which is 60 times as much as he rates the Force of the Heart at. Then deducting 45,000l. for the adventitious Help of the Muscular Elastic Coat of the Arteries, he leaves the Heart with a Force of 3,000l. to overcome a resistance of 135,000l. that is, with 1, to remove 45.
This stupendous Effect he contents himself to ascribe to the Energy of Percussion. But, had he proceeded in his Calculation to the Veins, which he allows to contain constantly a quantity of Blood, quadruple to the Contents of the Arteries, and to which this Energy of Percussion does either not reach at all, or but very languidly, he might probably have seen