Class IV. 2. 1. 10. OF ASSOCIATION. 405 



ly retarding his pulfe. This curious circumftance cannot arife 

 from the general effect of exercife, or fatigue, as in thoie cafes 

 the pulfe becomes weaker and quicker ; it muft therefore be af- 

 cribed to a degree of vertigo, which attends all thofe modes of 

 motion, which we are not perpetually accuftomed to. 



Dr. Currie has further obferved, that " in cafes of great de- 

 bility the voluntary mufcular exertion requifite in a fwing pro- 

 duces wearinefs, that is, increafes debility ; and that in fuch in- 

 ftances he had frequently noticed, that the diminution of the fre- 

 quency of the pulfe did not take place, but the contrary." Thefe 

 circumftances may thus be accounted for. 



The links of affcciation, which are effecled in the vertigo oc- 

 casioned by unufual motion, are the irritative motions of the 

 fenie of vifion, thofe of the ftomach, and thofe of the heart and 

 arteries. When the irritative ideas of vilion are exerted with 

 greater energy at the beginning of vertigo, a degree of fenfation 

 is excited, which is of the pleafurable kind, as above mentioned $ 

 whence the aflbciated trains of irritative motions of the ftomach, 

 and heart, and arteries, act at firft with greater energy, both by 

 direcl; fympathy, and by the additional fenforial power of fenfa- 

 tion. Whence the pulfe of a confumptive patient becomes ftrong- 

 er and confequently flower. 



But if this vertigo becomes much greater in degree or dura- 

 tion, the firft link of this train of aftociated irritative motions 

 expends too much of the fenforial power, which was uiiuJly em- 

 ployed on the whole train ; and the motions of die ftomach be- 

 some in confequence exerted with lefs energy. This appears, 

 becauie 111 this degree of vertigo ficknefs fupervenes, as in fea- 

 ficknefs, which has been (hewn to be owing to lefs energetic ac- 

 tion of the ftomach. And the motions of the heart and arteries 

 then become weaker, and in confequence more frequent, by their 

 direcl: fympathy with the leiiened actions of the ftomach. See 

 Supplement, I. 12. and Clafs II. 1. 6. 7. The general weak- 

 nefs from fatigue is owing to a fimilar caufe, that is, to the too 

 great expenditure of fenforial power in the increafed actions of 

 one part of the fyftem, and the confequent deficiency of it in 

 other parts, or in the whole. 



The abatement of the heat of the ikin in hectic fever by 

 fwinging, is not only owing to tlie increafed ventilation of cool 

 air, but to the reverfe fympathy of the motions of the cutaneous 

 capillaries with thofe of the heart and arteries ; which occurs in 

 all fevers with arterial debility, and a hot or dry ikin. Hence 

 during moderate fwinging the action of the heart and arteries 

 becomes ftrongerand flower, and the action of the capillaries, 

 which was before too great, as appeared by the heat of the fltin, 



is 



