NO. 23 INFLUENCE OF ATMOSPHERE ON HEALTH 3 



Sherrington points out that a sense organ — the receptor apparatus 

 ■ — is not stimulated unless there is a change of rate in the transfer- 

 ence of energy ; and that a change of rate, to be effectual, must 

 occur in most cases with considerable quickness ; " otherwise there 

 is a mere unperceived shift in the stationary equilibrium which 

 forms the resting zero of the sensual apparatus." " Both for sensa- 

 tion and for reflex action a function in the threshold value of stim- 

 ulus is time as well as intensity and quantity. If a weak agent is to 

 stimulate, its application must be abrupt." 



Thus the slow changes of barometric pressure on the body surface 

 originate no skin sensations, though such changes of pressure, if 

 applied suddenly, are much above the threshold value for touch. A 

 touch excited by constant mechanical pressure of slight intensity 

 fades quickly below the threshold of sensation. Thus the almost 

 unbearable discomfort which a child feels on putting on for the first 

 time a " natural " wool vest fades away and is no longer noticed 

 with continued wear. Thomas a Becket soon must have become 

 oblivious to his hair shirt and its harbingers. It is not the wind 

 which God tempers to the shorn lamb, but the skin of the lamb to 

 the wind. 



" There streams constantly from the body through the skin a cur- 

 rent of thermal energy much above the threshold value of stimuli 

 for warmth sensations ; yet this current evokes — under ordinary 

 circumstances — no sensation. It is the stationary condition, the 

 fact that the transference of energy continues at constant speed, 

 which makes it unperceived." The inflow of sensations keeps us 

 active and alive, and all the organs working in their appointed 

 functions. Those from the great cutaneous field are of the highest 

 importance. The salt and sand of wind-driven sea air and sea baths 

 act on the skin and brace up the body. The changing play of wind, 

 of light, of cold and warmth, stimulate the activity and health of 

 mind and body. Monotony of occupation and external conditions 

 for long hours destroy vigor and happiness and bring about the 

 atrophy of disuse. Daily observation shows us that a drayman, navvy, 

 or policeman can live in London or any other big city strong and 

 vigorous, and no less so than in the country: the brain worker, too, 

 can keep himself perfectly fit if his hours of sedentary employment 

 are not too long and he balances these by open air exercise. The 

 horses stabled, worked, and fed in London are as fine as any in the 

 world: regular open-air exercise and proper feeding and housing 

 ensure the health and fitness of a horse, and no less of a man. 



