EXTRACT LI. 



ON MAL DE MER OR SEA SICKNESS. 



THIS is an affliction, we can scarcely call it an affection, 

 with which the human family and some of their lower 

 neighbours have been familiar since its members ' went 

 down to the sea in ships" or trusted themselves to less 

 substantial means of support on the undulating surface 

 of river, lake, or sea. 



Its causation is but too apparent, and its incidence what 

 would seem somewhat capricious, thus, one or a few only 

 may succumb to it out of a large party, while one or a 

 few only may escape out of a large party, when the 

 exciting causes have been but slightly modified or 

 intensified. 



It is essentially of nervine origin, and due to the 

 difference in the specific gravity of the various component 

 parts or organs of the human body whereby their various 

 rates of upward and downward movements are irregularly 

 effected in every succeeding rise and fall of the craft, 

 engendering mechanical jarring and concussion, and finally 

 affecting the neuro-muscular economy to such an extent 

 that general materio-dynamic demoralisation ensues, with 

 the familiar consequences. 



To illustrate this theory of its causation, we may fill 

 a hat, or other hollow receptacle, with a dozen substances 

 of different weights and differing sizes and densities, and 

 throw them up out of the receptacle with some force, and 

 it will be seen that they do not all reach the same height 

 or traverse space at the same rate of speed, and that in 

 descending their rates of movement are in the inverse 



