HEADACH. 543 



vomiting, &c. On the same cause, perhaps, but with a greater 

 degree of obstruction, depends the headach which commonly 

 proceeds from fits of the spasmodic asthma. 



" To these we may add another set of occasional causes, 

 quite different from the former, and, perhaps, directly opposite. 

 Of this kind are, sudden fear, sudden grief, and particularly any 

 subject of anxiety. To these we may add, excess of study, not 

 only such as is keen and intense, but that which is long pro- 

 tracted and accompanied with watchings. This last is a frequent 

 cause ; and yet not less frequently the headach is occasioned by 

 too much sleep, and, in some people, even by the ordinary 

 sleep. Sleeping at unusual hours, as in the afternoon, is very J 

 apt to bring it on ; an abstemious way of life is another cause ; ' 

 and we have known several instances of persons cured of the 

 headach by using a fuller diet ; it may also be occasioned by 

 evacuations, if too large and too long continued. 



" We mentioned above, that headach frequently proceed- 

 ed from obstruction of some usual evacuation ; yet it arises no 

 less frequently from too copious evacuations, and none are more 

 subject to it than women witb too copious a menstrual flux, or 

 men with an hasmorrhoidal flux. In this case it attacks women \ 

 at the going off of menstruation, as in. the other it did in the 

 beginning. In short, there are instances of its being occasion- 

 ed by every thing that weakens the body. One of the most 

 frequent causes is the application of cold, particularly to the 

 head ; and this is relieved by warmth. To this we must add, 

 riding in the wind ; but whether this is merely from, the same 

 cause, is uncertain. Again, various odours, whether fragrant 

 or foetid, will sometimes produce headach ; wine too will have 

 this effect, either when taken in such a quantity only as to heat 

 the body, or after intoxication; opium will, in some persons, 

 produce similar effects, and probably other narcotics, and among 

 these the metallic, which is more evident from arsenic and mer- 

 cury than any other. All strong impressions on any of the j 

 senses, as violent noises, strong light or odours, may also be 

 occasional causes. There are some other circumstances more 

 difficult to be explained. Thus, whatever produces vertigo, 

 as the looking upon a stream of water, or from a great height, 

 will often occasion headach. Wkether these occasion slight 



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