STAGGERS, &c. 311 



" and this either proceeds from a caufe with- 

 ** oat the veflcls, viz. when the blood or any 

 '^ other fluid happens to break out of fome 

 *' veflel within the brain, or when there hap- 

 ** pv ns to be preternatural bones or tumours 

 *' bred and contained within the fcull, or 

 " any other extraneous matter that may, ia 

 " any rort, prefs upon the foft fubftance of the 

 *' brain, caufing thofe deadly diforders* But 

 " this is a fpecies that is incurable, and, for 

 " the moft part, .feizes faddenly without any 

 '^ foregoing tokens or warnings. Thus in an 

 *^ APOPLEXY fenfe and motion are in a manner 

 " quite loft, becaufe of the preffure that is 

 *' made upon the origin of all the nerves that 

 " arife from the head : but, in a vertigo, 

 " objedls that are at reft appear as if they 

 *^ were turning round, and by that means 

 *' occafion any creature to reel and ftagger; 

 *^ and this proceeds from the vibrations and 

 *^' tremors of the optic nerve, whereby the 

 " images falling not diredly but fucceffively 

 upon the different parts of the retina^ an 

 ' objedl that is at reft will therefore appear 

 as if turning round ; and this may be occa- 

 *' fioned either when an animal is fearful of 

 ^f falling, or from a repletion or overfulnefs 

 X 4 '' of 



