[ 2 3 I ] 
of the heart, and that the motion of the 
jugular veins was fynchronous to that of 
the arteries. 
Being aftonifhed at this unexpected phe- 
nemenon, he endeavoured to difcover by 
what rrlechanifm this reflux took place, 
and as he enjoys an eminent fhare of ad- 
drefs as well as of judgment, his efforts 
were crowned with fuccefs. 
Thus he obferved, that the left finus of 
the heart when turgid with blood, as it 
always is in the time of expiration by the 
emptying of the pulmonary into it, pufhes 
againfl: the poflerior paries of the right 
finus, which in confequence is raifed up 
an ifle or dam, which advances fo as to 
occupy the paffage which might remain 
between the two cavae, and fills it up in 
fuch a manner that it almofl touches the 
anterior face of the right ventricle almofl 
in its middle, and divides it into two 
parts, one fuperior, and the other infe- 
Ck 4 rior. 
