18 R. M. Bache on Sea-sickness. 1 



heavenly bodies are not appreciable by our senses. We have 

 conception of them through the mind, but not through sight 

 or hearing, therefore I have chosen the motion of railway trains 

 for th§ purpose of illustrating the effect of the mere appearance 

 of motion. Standing as near, or as far off, as one pleases, from 

 a train of cars in rapid motion, no more nauseating effect is pro- 

 duced upon the spectator, than by the sight of any object at rest. 

 Yet the appearance of motion is nauseating in two cases — but 

 these are where the idea of motion of the body is involved, that 

 is, where motion of the body of the observer is either in debate 

 by the mind, or acknowledged by the mind and the motion is 

 not felt. If this can be made to appear, it is additional proof, 

 that the mere appearance of motion is not nauseating, or as I 

 shall henceforth express it for convenience, the appearance of 

 motion is not nauseating " per se." As an example of the first 

 case— that the appearance of motion is nauseating " when motion 

 of the body of the observer is in dehate by the mind"— take the 

 following : In a dimly lighted depot, two trains of cars stop side 

 by side—presently one starts— so gently that an occupant of one 

 of the trains cannot decide whether it is his own train which is in 

 motion, and consequently whether it is his own body which is in 

 motion or whether the motion perceived, is that of the other train. 

 This produces a sensation of uncomfortableness — of giddiness- 

 indicative that nausea would result if the effect were continued. 

 At all events, it produces an impression of motion of the body, 

 which impression is derived through the instrumentality of the 

 sight, and which impression affects the nervous system unpleas- 

 antly—yet the body of the observer may have been at rest all the 

 while. As an example of the second case— the assertion " that 

 the appearance of motion is nauseating when motion of the body 

 of the observer is acknowledged by the mind, and the motion 

 is not felt;' one illustration, as in the first case, will suffice. 

 In the slight trembhng of an earthquake, when the jar would 

 have escaped notice, but for the faint oscillation of a chandelier 

 which calls attention to the existence of an earthquake— this 

 oscillation through the impression which it gives the observer, 

 that his body is in motion, often causes the sensation of nausea. 

 It is impossible that the motion of the body of the observer could 

 cause the sensation, for the case spoken of is one where the ex- 

 istence of the earthquake would not have been known, but for 

 the oscillation of the chandelier. The sensation could not have 

 proceeded from the mere perception of the motion of the chan- 

 deher, because such an object can be viewed while swinging 

 violently, without any sensation being produced, other than the 

 perception of its swinging. 



The cause of the disagreeable sensations just described, is ow- 

 ing to the fact that nature requires our senses to keep pace. The 

 sight must not proclaim what the feeling does not at once cor- 



