ws a tendency of the constitution to inirritability; that
is to debility, or deficiency of sensorial power, and is to be relieved by
small doses of steel and opium.

The venereal orgasm of birds and quadrupeds seems to commence, or return
about the most powerful lunations at the vernal or autumnal equinoxes; but
if it be disappointed of its object, it is said to recur at monthly
periods; in this respect resembling the female catamenia. Whence it is
believed, that women are more liable to become pregnant at or about the
time of their catamenia, than at the intermediate times; and on this
account they are seldom much mistaken in their reckoning of nine lunar
periods from the last menstruation; the inattention to this may sometimes
have been the cause of supposed barrenness, and is therefore worth the
observation of those, who wish to have children.

III. We now come to the periods of diseased animal actions. The periods of
fever-fits, which depend on the stated returns of nocturnal cold, are
discussed in Sect. XXXII. 3. Those, which originate or recur at solar or
lunar periods, are also explained in Section XXXII. 6. These we shall here
enumerate; observing, however, that it is not more surprising, that the
influence of the varying attractions of the sun and moon, should raise the
ocean into mountains, than that it should affect the nice sensibilities of
animal bodies; though the manner of its operation on them is difficult to
be understood. It is probable however, that as this influence gradually
lessens during the course of the day, or of the lunation, or of the year,
some actions of our system become less and less; till at length a total
quiescence of some part is induced; which is the commencement of the
paroxysms of fever, of menstruation, of pain with decreased action of the
affected organ, and of consequent convulsion.

1. A diurnal fever in some weak people is distinctly observed to come on
towards evening, and to cease with a moist skin early in the morning,
obeying the solar periods. Persons of weak constitutions are liable to get
into better spirits at the access of the hot fit of this evening fever; and
are thence inclined to sit up late; which by further enfeebling them
increases the disease; whence they lose their strength and their colour.

2. The periods of hectic fever, supposed to arise from absorption of
matter, obeys the diurnal periods like the above, having the exacerbescence
towards evening, and i