ON SEASICKNESS. QQ^ 



Part II. On Seasickness, 



The second remark which I have to offer to the society Seasickness, 

 relates to seasickness, the cause ot" which has not hitherto 

 been fully explained ; and although the explanation which 

 I aoi about to propose may not appear altogether satisfac- 

 tory to persons, who, when at sea, are also rendered giddy 

 by the incessant motion of the waves, and are consequently 

 liable to consider as cause and effect phenomena which in 

 their minds are constantly associated, yet the observation 

 on which it is founded may deserve to be recorded, on ac- 

 count of the degree of relief that may be obtained in that 

 inost distressing affection. 



After I had been harassed by seasickness during a short Power of re- 

 voyage for some days, and had in vain attempted to account s'stingits ef- 

 for the difference between the inexperienced passenger, and quired. 

 those around him more accustomed to the motion of the sea, 

 I imperceptibly acquired some power of resisting its effects, 

 and had the good fortune to observe a peculiarity in my 

 mode of respiration, evidently connected with the motion of 

 the vessel, but of which, in my then enfeebled state, I Avas Respiration 

 unable to investigate either the cause or consequence. In ^ff^cted by the 



„ r' 1- 1T1 -, f motion of a 



waking irora a state ot very disturbed sleep, I found that vessel j 



my respirations were not taken with the accustomed uni- 

 formity, but were interrupted by irregular pauses, with an 

 appearance of watching for some favourable opportunity for 

 making the succeeding effort; and it seemed as if the act 

 of inspiration were in some manner to be guided by the 

 tendency of the vessel to pitch with an uneasy motion. 



The mode by which I afterward conceived, that this action 

 could primarily affect the system, was by its influence on which influ- 

 the motion of the blood; for, at the same instant that the ^"^f- ^1^^ T/*,. 

 chest is dilated for the reception of air, its vessels become blood, 

 also more open to the reception of the blood, so that the 

 return of blood from the head is more free than at any 

 other period of a complete respiration. On the contrary, 

 by the act of expelling air from the lungs, the ingress of 

 blood is so far obstructed, that, when the surface of the 

 brain is exposed by the trepan, a successive turgescenceand 

 subsidence of the brain is seen in alternate motion with the 



different 



