ON SEASICKNESS. 295 



cause a portion of its gravity is then employed in occasioning 

 its descent along with the vessel ; and, accordingly, if it 

 were confined in a tube closed at bottom, it would no longer 

 press with its whole weight npon the lower end. In the 

 same manner, and for thte same reason, the blood no longer 

 presses downwards with its whole weight, and will be driven 

 upwards, by the elasticity which before was merely sufficient 

 to support it. 



The sickness occasioned by swinging is evidently from Sickness frem 

 the same causes as seasickness; and that direction of the ®"*"'=''"^* 

 motion, which occasions the most piercing sensation of unea* 

 siness, is conformable to the explanation above given. 



It is in descending forward, that this sensation is per-^ 

 ceived ; for then the blood has the greatest tendency to move 

 from the feet toward the head, since the line adjoining theni 

 is in the direction of the motion. But when, in the descent 

 backwards, the motion is transverse to the line of the 

 body, it occasions little comparative inconvenience, because 

 •the tendency to propel the blood toward the he^d is then 

 inconsiderable. 



The regularity of the motion in swinging afforded me an Not fully pve- 

 apparently favourable opportunity for trying the effect of J^j"^^- j^^' '"* 

 inspiration ; but although the advantage was manifest, I 

 must confess, it did not fully equal the expectations I had 

 formed from my experience at sea. It is possible, that the 

 suddenness of the descent may in this case be too great, to 

 be fully counteracted by such means ; but I am Inclined to Contents of 

 think, that the contents of the intestines are also affected by t'le intestme- 

 , lilt 1 • 1- 1 1 1- artacted also. 



the same cause as tlie blood; and it these have any qirect 



disposition to regurgitate, this consequence will be in no 

 degree counteracted by the process of respiration. 



A friend of mine informed me, that he had endea- Effect on the 

 voured to counteract this mechanical effect upon the sto- ■'^'o'"^'^^ '" 

 mach, and had experienced immediate relief .from a slight counteracted. 

 degree of seasickness, by lying down npop the deck wifh 

 his head towards the stem of the vessel ; by means of which, 

 upon pitching, he was in the attitude of a person descend- 

 ing backwards in a swing. 



Whether the stomach be or be not thus primarily affected, AfFect on the 

 Qr only by sympathy with the brain, the sensation of sinkini; s*"""'''' '" 



is 



