He recommenced with the statement of the difference with which water flowed from a reservoir through tubes of equal calibre, but unequal lengths; and of the effect of pressure on elastic tubes, shewing that the impediment to the transmission of fluid through them was proportioned to their length. He stated that the obstruction at the turn of a tube, was proportioned to the acuteness of the angle. He then inferred that the arteries were in circumstances to render the delivery of blood unequal, unless there was a living property additional to the hydraulic laws.

Then, referring to the effect of capillary attraction, he argued, that if the law prevailed in the animal body as in dead tubes, then, on estimating the length of vessels of capillary size, and the attraction existing between solid and fluid, the circulation could not go on.