Cruise ship motion sickness

Cruise ship motion sicknessSome persons get sick on railway trains in motion. The frequency and severity of the cases are proportional to the frequency of curves and grades, and also to the speed. The variations dependent on curves and grades are thirdclass movements.

Third-class motions on ships are ordinarily such that each variation may be anticipated and adjusted for. The subject becomes cognizant of the variations chiefly by the tactile and kinaesthetic senses of whatever parts of the body are in contact with the object whose motion is communicated to him; by these means chiefly, and in addition, under some circumstances, by the sense of sight. Some attention to the motions facilitates the recognition of their variations.

Any variation recognized soon enough, the adjustment to it takes place automatically. The motions, being in the first place of third class, become motiorjs of second class to the extent that the subject recognizes them and adjusts to them. To him who is for the first time on a ship the motions are of third class, while the same are to the experienced voyager motions of the second class: recognition of and adjustment to them in his case are automatic and unconscious.

It now seems quite plain that the sickness is not due to motion per se, else it would make the sailor sick also, because he is subjected to the same motion. And it is equally plain that the sickness is due to the condition which distinguishes third-class motions, namely, the condition of being passive mentally. Many persons get sick riding inside of stage coaches or carriages; I have been unable to learn of anyone ever getting sick riding on the outside with the driver. The cause of sickness in staging lies evidently in the difference between riding in and riding outside, and what is this difference?

On the outside the subject foresees every start and stop, every curve in the road, every elevation, depression, and in fact everything that will influence the motion of the coach and therefore of himself. Foreseeing all these there occur in him accommodating adjustments in accordance. On the inside nothing is foreseen; therefore all the variations of motion affect the subject unawares, each resulting in shock, which by accumulation amounts to illness.