On the salutary Effects of Ridings '&c, 44$ 



In thus referring the stinsalions of sea-sickness in so 

 gre.it a degree to the agency of mere mechanical pressure, 

 1 feci conlirined by considering the consequence of an op- 

 posite motion, whicli, by too quickly wiihdrawing blood 

 fron) the hend, oceasiuns a tendency to faint, or that ap- 

 proach to fainting, which amounts to a momentary giddi- 

 ness with diminuiion of muscular power. At a time when 

 1 was much fatigued by e;(ercise, I had occasion to run to 

 some distance, and seat myself under a low wall for shelter 

 from a very heavy shower. In rising suddenly from this 

 position I was attacked with such a degree of giddiness, 

 that I involuntarily dropped into my former posture, and 

 w as instantaneously reieved, by return of blood to the head, 

 from every sensation of uneasiness. 



Since that time, the same affection has frequently oc- 

 curred to me ill slighter degrees, and I have observed, that 

 it has always been under similar circumstances of risin-g 

 suddenly from an inclined position, after some degree of 

 previous fatigue. Sinking down again immediately re- 

 moves the giddiness ; and then, by rising a seconcj tin%e 

 more gradually, the same sensation, is avoided. 



Part III. On the salutary Effects of Ridings and other Modes 



of Gestation. 



In the preceding instances of distuibing the circuiatiaii 

 of the blood, by external niotion, the effect is disagreeable, 

 and propuriicnally prejudicial. There may indeed be cases 

 of disorder, in which it w»ll be salutary, but these are pro- 

 bably less frequent than is generally supposed. 



In the otiservaiions whicli follow, general opinion will 

 concur with me, on the benefit derived from external or 

 passive motion, and I hope that, in ascribing its good 

 effects to their true cause, T shall enable others to make a 

 valuable distinction, which has not yet been preserved with 

 due care, between one motion which is salutary, and an- 

 other which is very frequently pernicious. For, although 



inany people could forctel rt by an alrcratinn in their stomachs; an cffFect 

 wliich (it is added) ,;lvVrt)» accompanieo the wavC'like niotion of eart!*- 

 q-.iakes, wliea it is so weak as to be uncertainly dibtinguishahle.'* (Michel!, 

 3>hil.Trsnb. vokU 610) 



It beeins thai the vapours to which these tremendous concussions are 

 owing, inimeirse i*i qurintity, and uf prodigious I'orce, btiug for a time coii- 

 lineJ on all sides, elev .le the suiface of a tountry to a vast eitent unt't 

 thev either find venr,or meet with some partial cmjreof condensation ; and 

 hence the alreiivite htaviu'^ and subiidence of the ground will produce 

 ijiudi iIa; sit.ji«i cilicti as »i'C r;j;i)j, uad fJIizig of the swell at sea. 



thi 



