( 66o ) 
explains ; fo that there muft, in general, be a difference 
in thecircumftances of Difeafes, though of the fame De- 
nomination, which happen in either of them. But to 
fign a reafon why we have Periodical returns.he confiders, 
First, That we generally Eat at determinate Times, 
irooi whence the admifhon, as well as diOribution of the 
Nutritious Juice (which he before fupp ;(ed to be by the 
Nerves^) muft be Periodical. But tills being not fuffici- 
ent, fince moft perfons eac oftner than once a day, he 
confiders, Secondly, That we deep ordinarily but once in 
24 Hours, at which time the Brain being relaxed, admits 
the Suppliments of Nouriftiment for the next day, as up- 
on w aking it begins, and all day after continues gently to 
protrude it Cat leaft more vigoroufly) through the whole 
Fibrous Syfteme ; in which time it advances in it's Matu- 
ration, as ufually toward becoming a fit Nutritious 
Juyce, fo now, being in fome degree incongruous, to- 
ward a Febrifick Ferment; fo that, ceteris paribus, a Di- 
ary Period (unJefc when a greater, or more depraved, 
quantity than ufual of Heterogeneous matter abounds; may 
be hence expected. But to determine the reafon of lon- 
ger Periods, he fuppofes, Thirdly, Vie muft have recourfe 
to the different Conftitutions oi the year ; And in the 
Spring the Air abounding (by general confenO wit,*! Ni- 
trous Particles, which though c£Kve, and thence a^t to 
exagitate and exalt a Morbifick Ferment, yvt helping to 
constitute the Principles of Vitality, and in fome degree 
corroborative of the Tone of tly. Glandules, they hinder, 
in fome meafure, the encreafe of the Morbid matter ia 
them, fo that fo much cannot be congefted int\&Sy(hme 
of the Nerves ^.nd Fibres as to rife to a degree of Vesica- 
tion able to produce a Paroxyfwe ; whence there is a ne- 
cefiityof a fecond Night's fuppliss to yield a proportion 
nable quantity to the effed:. But in the Autumn, Acids 
abounding, which both in fome degree reprefs Fermerv 
tation, and withal help to conftringe the Tone of the 
parts, 
