374 DISEASES CLASS IV. i. 2. 3. 



lates the furfacc of the eye, at the fame time the increafed abun- 

 dance of tears ftimulates the pundta lachrymalia into greater ac- 

 tion ; and the fluid thus abforbed ftimulates the lachrymal fac, 

 and its nafal duel: in the nofe into greater action. In a contra- 

 ry direction of this ch.^n of aflbciation the prefent increafe of 

 action is induced. Firft, the nafal duel: of the lachrymal fac is 

 excited into increafed action by fome pleafurable or painful idea, 

 as defcribed in Seel. XVI. 8. 2. 2d. The puncta lacrymalia 

 or other extremity of the lachrymal fac fympathizes with it (as 

 the two ends of all other canals fympathize with each other.) 

 3d. With theie increafed motions of the puncta lacrymalia thofe 

 of the excretory duel: of the lachrymal gland are aflbciated from 

 their having fo perpetually acted together. And, laftly, with 

 the increafed actions of the excretory duel: of this gland are af- 

 ibciated thofe of the other end of it by their frequently acting 

 together ; in the fame manner as the extremities of other ca- 

 nals are aflbciated, and thus a greater flow of tears is poured in- 

 to the eye. 



When a flow of tears is produced in grief, it is believed to 

 relieve the violence of it, which is worthy a further inquiry. 

 Painful fenfations, when great, excite the faculty of volition ; 

 and the perfon continues voluntarily to call up or perform thofe 

 ideas, which occafion the painful fenfation ; that is, the afflict- 

 ed perfon becomes fo far infane or melancholy ; but tears are 

 produced by the fenforial faculty of aflbciation, and fhew that 

 the pain is fo far relieved as not to excite the exceffive power of 

 volition, or infanity, and are therefore a fign of the abatement of 

 the painful (late of grief, rather than a caufe of that abatement. 

 SeeClafsIII. I. 2. 10. 



2. Sternutatio a lumine. Some perfons fneeze from looking 

 up at the light Iky in a morning after coming out of a dark 

 bed room. The olfactory nerves are brought into too great ac- 

 tion by their fympathy with the optic nerves, or by their refpec- 

 tive fympathies with fome intervening parts, as probably with 

 the two extremities of the lachrymal fac ; that is, with the punc- 

 ta lacrymalia and the nafal duet. See Clafs II. I. i. 3. 



3. Dolor dcntium aftrichre. Tooth-edge from grating founds, 

 and from the touch of certain fubftances, and even from im- 

 agination alone, is defcribed and explained in Sect. XVI. 10. 

 The increafed actions of the alveolar veflels or membranes are 

 aflbciated with the ideas, or fenfual motions of the auditory 

 nerves in the firft cafe , and of thofe of the fenfe of touch, in 

 the fecond cafe j and by imagination, or ideas exerted of painful 

 fenfation alone, in the laft. 



Rifusfardonicus* A difagreeable fmile attends inflammations 



of 



