[ 246 3 
by the known meafures of time. Not*, 
withflanding, it appears that fometimes 
this fluid does not poffefs its ordinary ve¬ 
locity, but even common electricity has 
fometimes a loitering pace not eafily recon¬ 
cilable with its common immeafurable 
velocity. 
The inftances of epilepfies being ex¬ 
cited by an aura which, efcaping from the 
extremities or feme other part of the body, 
proceed flowly to the brain, have nothing 
to do with the nervous fluid, and do not 
prove its flownefs. This aura (if fuch 
be not an illufion in the patient) is the ef¬ 
fect of fome other fubtle principle formed 
in the nervous fubftance by fome accident. 
It will be eafy to convince ourfelves of 
this, if we confider the matter more clofely. 
The patient feels that the aura afeends, 
there is then another fluid which makes a 
Conflant impreflion upon the brain, fo that 
he is advertifed at every inftant of what 
