INTRODUCTION. 1 1 



below "by the Captain on account of the stormy character of 

 the weather, and on whom the hatches were closed down, 

 although the cabin which was crowded by them had scarcely 

 any other means of ventilation. Out of 150 of these unfor- 

 tunates, no fewer than 70 died of suffocation before the 

 morning, a catastrophe only second to that which occurred 

 in the "Black Hole of Calcutta," in which 123 out of 146 

 died during one night's confinement in a room eighteen feet 

 square, provided with only two small windows. Yet the 

 Captain of the " Londonderry " was acquitted of all blame ; 

 since he had done what seemed to him best for the welfare of 

 his passengers, the result being due simply to his astound- 

 ing ignorance of the fact that men cannot live without having 

 air to breathe. Not a year passes without the occurrence of 

 numerous deaths from the like cause ; and yet these are 

 really insignificant, when compared with the vast amount of 

 disease which is constantly attributable to inattention, on the 

 part of individuals, to those simple means of securing an 

 adequate supply of air which are within the reach of every 

 one. And when we bear in mind that the respiratory func- 

 tion is only one of the processes whose due performance has 

 to be provided for, and that the regulation of the food and 

 drink, of the excretions, of clothing and temperature, of 

 exercise (bodily and mental) and repose, and of the repro- 

 ductive functions, all fall within rules which it is the pro- 

 vince of Physiology to prescribe, we see how vain it is to 

 expect that the body can be maintained in health, without 

 some acquaintance with that science, or at least with the 

 rules which it lays down. For, although it is quite true that 

 man has within himself certain instincts which afford him a 

 considerable measure of guidance in all these particulars, 

 hunger and thirst, for example, leading him to take the 

 sustenance which his body requires, weariness tempting him to 

 needed repose, and so on, yet it is no less certain that in a 

 state of artificial civilisation these instincts are so often over- 

 borne by acquired tastes, or by the pressure of other circum- 

 stances, that they cannot alone be safely relied on. Hence it 

 is all the more important that the rules for preserving health 

 should be based on an intelligent knowledge of Physiological 

 principles ; otherwise, }ike the natural instincts, they are likely 

 to be put aside as occasion prompts ; whereas, in proportion as 



