Sect. XXXV. 2. i. 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 thoie pains, which continue feme 

 ;time without being attended with inflammation, fuch as the pain 

 at the pit of the ftomach from a (lone at the neck of the gall- 

 bladder, and the pain of ftrangury in the glans penis from a {lone 

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

 which is affected iecondarily, is believed to be much more fen- 

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

 logue of difeaies, Clafs II. 1. 1. 11. 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. 1. 1. 6. 



The lait tooth, or dens fapientia?, of the upper jaw moil fre- 

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

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

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

 When a tooth in the upper jaw is the £aufe of the headach, a 

 ilighter pain is fometimes perceived on the cheek-bone. And 

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

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

 are attached near the jaws. But the ciavus hystericus, or pam 

 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 ; of which I fhall 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 parietal bone, "which had continu- 

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

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

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

 ftriking them with a tea-fpoon, and fearing bad confequences 

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

 lad tooth of the under-jaw on the affected fide; which was 

 done without any good effecl:. She was then directed to lofc 

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

 about 6© drops of laudanum were given her, with large dofes 

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

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



with 



