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punctured for the hydrocephalus, might probably be, 
that all the water had been drawn off at once ; and 
that the brain had been left, as it were, uncover’d, 
and expofed to the impreflions of the air, which 
muft neceflarily fill the wide fpace, that had been 
occupied by the water ; lince, in this cafe, the inte- 
guments could not be prelfed clofe on the contained 
parts, as it happens to the integuments of the abdo- 
men after the punCture in the afcites. Wherefore,, 
lince I was prevailed on to make the punCture, I re- 
vived to draw the water by little and little, at dif- 
ferent times diilant from each other ; and in the 
intervals of thefe evacuations to comprefs the integu- 
ments with a proper bandage, to make them come 
near the brain. 
The common trocarts did not feem proper to ful- 
fil thefe views. I was of opinion, that pundtures 
often repeated in thefe nervous parts were dangerous r 
befides, as the integuments of the head were thin, 
and upon the flretch, the opening being once made 
would never clofe fufficiently to flop the evacuation,, 
when the canula was removed ; and if I left the ca - 
nula in the orifice, and flopp’d it with a flopple, 
this fame difpofition of the integuments would fuffer 
the water to ouze out between them and the fides 
of the canula : thus would the evacuation become 
total, in fpite of me, whatever method I ufed with 
the trocarts already known. Thefe reflections made 
me contrive the following inflrument. 
It is a new trocart, reprefented by Fig. 2. and 
which has this peculiarity, that the canula is much 
fhorter than ordinary. This canula is reprefented 
feparate in Fig. 3. : but there ought to be feveral, 
of 
