r ^ 5 ^ > 
bundance of Pleafure and Surprize-; for the Blood-Wiii 
v/as not only moved in that part where the Valve i% 
but the Parts about the Blood-VelTel, of the breadth of 
four or five Hairs/ were likewife moved or ftirr’d ; from 
vy hence it appear’d, that at every Protrufion of Blood' 
into the Heart thro’ tlie Valve, the Blood flood ftill a- 
bout an inflant of time, and that the fame Blood, fal* 
ling thro’ the Valve, ran with great fwiftnefs, and was 
thickeft juft at its Protrufion out of the Valve, but ran 
thinner or flenderer like the Figure of a Pear; and the 
Vein that received this Protruded Blood, was not intire- 
ly fill’d with it, but feemM for a fmall foace to -be as it 
were empty, and the Parts of it contratted, which we 
cou’d perceive for a fmall time, and further obferving it, 
faw the Blood run flowly and leifurely along the fame 
Vefiel, 
From tills Obfervation I imagin’d, that tlie fame thing 
happen’d in the Heart of a Humane Creature, that 
there is a gentle and flow Protrufion of the Blood out 
the Heart into that V-eflel, which we call the Artery, 
and confequently that there is no fuch motion there, as 
what is called a Pulfe, and which is felt in the extreme 
Parts of the Body; but that the fo named Puifes are 
only caufed by the Protrufion of the Blood thro’ the 
Valves that are in the Veins, but I never obferved any 
violent or fwift Protrufion of the Blood into the Arte- 
ries, as often as I have viewed the Circulation thereof : 
and tho’ the Blood, by the Contra£Hon of the Heart, 
be fuddenly and haftily protruded out of it, yet its flow- 
ly carried into the Artery ; whereas on the contrary, it 
runs into the Heart from the Veins with a violent and 
fwift Courfe; from whence it happens, as I fuppofe, 
that the remaining part of the Blood in the Veins being 
unable to follow with fo fwift a Motion, are as it were 
violently and per faltum drawn or forced thro* the 
Valves, and that it is this fort of Motion which we take- 
for.Pulfcs in the Arteries. That 
