180 EFFECTS OF WEATHER CHAP. 5. 



A change of wind, particularly a change 

 from any other quarter to East, makes most 



constitutions, I have frequently noticed a remarkable variety 

 in the appearance of the hairs on the head : they have* 

 appeared, at times, diminished in quantity : at others, super- 

 abundant. I have examined them carefully, in each of their 

 states, and found their apparent diminution to consist in the 

 shafts themselves becoming smaller, dryer, losing their tension, 

 and lying in closer contact. I was once inclined to attribute 

 their closer contact to a diminution of their electricity, by 

 which they would become less mutually repulsive : this, 

 however, does not seem sufficient to account for their decrease 

 in size. The shaft may possibly be organized throughout, 

 and its enlargement may be caused by an increased action of 

 its vessels ; there may also be an aeriform perspiration into its 

 cavity, on an increase of which it may be more distended : 

 and the increased size and tension of the shaft may result 

 from the co-operation of these two causes. The increased 

 size, strength, and tension of the hair, appear to accompany 

 health, while the opposite state seems to be connected with 

 disorder. The sympathies between the skin and the stomach 

 have been frequently adverted to by physiologists : the skin 

 has been found to be alternately dry and hot, moist and hot, 

 dry and cold, and moist and cold ; and these varieties have 

 been attributed to varieties in a state of the stomach, between 

 which and the skin a very direct symathy is believed to exist. 

 But the varieties in the appearance of the hah do not appear 

 to have been noticed. I have observed, that small doses of 

 mercury have changed the appearance of the hair very soon 

 after their administration. From being flaccid, dry, and 

 small, it has become tense, strong, and moister. Now mer- 



