HEADACII. 551 



be the constricting ; as there is then every proof that the blood 

 is not impelled into the head with the same impetus as usual. 

 These pains thus differing as they recur at different periods of 

 the headach, are often connected with each other. Thus the 

 distending pain, as in haemorrhagies, by occasioning spasms, 

 lays the foundation for the constricting ; and the constricting 

 pain, when 'produced, proves a stimulus, and occasions the dis- 

 tending, as in fevers, inflammation, &c. When the distending 

 pain has continued in a part for any time, it leaves it in a state 

 to be affected by the constricting. Thus, acute rheumatism is 

 often attended by the chronic, and this by the palsy. This is 

 often propagated to the origin of the nerves ; so that other parts 

 are affected, as being connected with the sensorium commune ; 

 but these pains are often separate, and the constricting is fre- 

 quently found alone. 



" As headach proceeds from various causes, either of these 

 different states may prevail : thus, on the one hand, various 

 causes produce paroxysms of the distending pain, which were 

 marked out among the occasional causes, under the titles of 

 fulness, temporary rarefaction, and determination to the vessels 

 of the head. On the other hand, the constricting pain is occa- 

 sioned by cold, and all weakening causes ; by the passions, as 

 by fear and grief; by watchings, study, evacuations, abstinence; 

 by all such causes as dimmish the force of the nervous power, or, 

 by an external application, bring on a constriction of the part. 

 This pain thus produced, does not always prove a stimulus, or 

 bring on the distending pain. What has been here said, will 

 explain the various causes of headach. 



" In the febrile headach there is a more certain paroxysm ; in 

 the rheumatic, it is longer and more uncertain. With regard to 

 the headach depending on a topical fever, a question may arise, 

 what species of fever it might be, and when it properly partakes 

 of the nature and genius of an intermittent. Sauvages has been 

 so exact here as to distinguish both a Cephalcea and Hemicrania 

 intermittent., though there are several other periodical species. 

 This, when discovered, leads more directly to the method of 

 cure, and shows when the bark may be properly applied. 



" To distinguish then what periodical headachs immediately 

 partake of the nature of an intermittent, the following consider- 



