[ 22 9 ] 
he removed a large portion of the cranium 
of a whelp, and expofed the dura mater, 
where it covers the upper part of the brain. 
The longitudinal finus was almoft altoge¬ 
ther laid bare, and he imagined that he 
faw a pulfation in it; on applying the 
point of his finger, he became confident 
that there really exifted one, which was 
obfcure and interrupted. In order to 
difcover whether this proceeded from the 
motion of the brain, or was peculiar and 
proper to the finus, he made ah incifion 
into the dura mater, and bared the brain 
without injuring the finus. 
He was now enabled to perceive the 
motion of the brain, and at the fame time 
to judge by the touch of the motion of 
the finus, and became convinced that thefe 
motions were diftindt from, and indepen¬ 
dent of each other. 
To allure himfelf ftill farther of this 
circumftance, he divided the finus tranf- 
0^3 verfely 
