SECT. XXXV. 2. r. OF ASSOCIATION. 347 



the primary part of a train of fenfitive aflbciation ceafes, when 

 that of the fecondary part commences, are not unfrequent ; as 

 this is the general origin of thofe pains, which continue fome 

 time without being attended with inflammation, fuch as the pain 

 at the pit of the flomach from a (tone at the neck of the gall- 

 bladder, and the pain of (Irangury in the glaris penis from a (lone 

 at the neck of the urinary bladder. In both thefe cafes the part 

 which is aftedted fecondarily, is believed to be much more fen- 

 fible than the part primarily affected, as defcribed in the cata- 

 logue of difeafes, Clafs II. i. i. 1 1. and IV. 2. 2. 2. and IV. 

 2. 2. 4. 



The hemicrania, or nervous head-ach, as it is called, when it 

 originates from a decaying tooth, is another difeafe of this kind ; 

 as the pain of the carious tooth always ceafes, when the pain 

 over one eye and temple commences. And it is probable, that 

 the violent pains, which induce convulfions in painful epilepfies, 

 are produced in the fame manner, from a more fenfible part 

 fympathizing with a difeafed one of lefs fenfibility. See Cata- 

 logue of difeafes, Clafs IV. 2 2 8. and III. I. I. 6. 



The lad tooth, or dens fapientix, of the upper jaw moft fre- 

 quently decays firii, and is liable to produce pain over the eye 

 and temple of that fide. The lad tooth of the under jaw is alfo 

 liable to produce a fimilar hemicrania, when it begins to decay. 

 When a tooth in the upper jaw is the caufe of the headach, a 

 {lighter pain is fometimes perceived on the cheek-bone. And 

 when a tooth in the lower jaw is the caufe of headach, a pain 

 ibmetimes affects the tendons of the mufcles of the neck, which 

 are attached near the jaws. But the clavus hyftericus, or pain 

 about the middle of the parietal bone on one fide of the head, I 

 have feen produced by the fecond of the molares, or grinders, of 

 the under jaw j of which I (hall relate the following cafe. See 

 Clafs IV. 2. 2. 8. 



Mrs- , about 30 years of age, was feized with great pain 



about the middle of the right pariecal bone, which had continu- 

 ed a whole duy before I faw her, and was fo violent as to threat- 

 en to occafion convulfions. Not being able to deleft a decay- 

 ing tooth, or a tender one, by examination with my eye, or by 

 {Inking them with a tea-fpoon, and fearing bad confequences 

 from her tendency to convulfion, I advifed her to extract the 

 laft tooth of the under jaw on the affefted fide ; which was 

 done without any good effect. She was then dire&ed to lofe 

 blood, and to take a brifk cathartic ; and after that had operated, 

 about 60 drops of laudanum were given her, with large dofes 

 of bark ; by which the pain was removed. In about a fortnight 

 fhe took a cathartic medicine by ill advice, and the pain returned 



with 



