454 THEORY OF FEVER. SUP I. 



IV. Return of the cold Fit. 



1. If the increafed aclion of the cutaneous and pulmom 

 capillaries, and of the heart and arteries, in febris irritativa, con- 

 tinues long and with violence, a proportional expenditure or ex- 

 hauftion of fenforial power occurs ; which by its tendency to in- 

 duce torpor of fome part, or of the whole, brings on a return of 

 the cold fit. 



2. Another caufe which contributes to iriduce torpor of the 

 whole fyftem by the fympathy of its parts with each other, is 

 the remaining torpor of fome vifcus ; which after the laft cold 

 paroxyfm had not recovered itfelf, as of the fpleen, liver, kid- 

 neys, or of the ftomach and inteftines, or abforbent veflels, as 

 above mentioned. 



3. Other caufes are the deficiency of the natural ftimuli, 

 hunger, thirft, and want of frefh air. Other caufes are grej 

 fatigue, want of reft, fear, grief, or anxiety of mind. And laftly, 

 the influence of external ethereal fluids, as the defect of exter- 

 nal heat, and of folar or lunar gravitation. Of the latter the 

 return of the paroxyfms of continued fevers about fix o'clock in 

 the evening, when the folar gravitation is the leaft, affords an 

 example of the influence of it ; and the ufual periods of inter- 

 mittents, whether quotidian, tertian, or quartan, which fo regu- 

 larly obey folar or lunar days, afford inftances of the influence of 

 thofe luminaries on thefe kinds of fevers. 



4. If the tendency to torpor of fome vifcus is confiderable, 

 this will be increafed at the time, when the terrene gravitation 

 is greateft, as explained in the introduction to Clafs IV. 2. 4. 

 and may either produce a cold paroxyfm of quotidian fever ; or 

 it may not yet be fufficient in quantity for that purpofe, but may 

 neverthelefs become greater, and continue fo till the next period 

 of the greateft terrene gravitation, and may then either produce 

 a paroxyfm of tertian fever ; or may ftill become greater, and 

 continue fo till the next period of greateft terrene gravitation, and 

 then produce a paroxyfm of quartan ague. And laftly, the pe- 

 riodical times of thefe paroxyfms may exceed, or fall fhort of, 

 the time of greateft diurnal terrene gravitation according to the 

 time of day, or period of the moon, in which the firft fit began ; 

 tint is, whether the diurnal terrene gravitation was then in an 

 increafmg or decreafmg ftate. 



V. Senfation excited in Fever. 



i. A curious obfenration is related by Dr. Fordvc* in his 



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