the lungs, or our desire of fresh air, but also by our attention to the
hourly objects before us. Hence when a person is earnestly contemplating an
idea of grief, he forgets to breathe, till the sensation in his lungs
becomes very urgent; and then a sigh succeeds for the purpose of more
forceably pushing forwards the blood, which is accumulated in the lungs.

Our times of respiration are also frequently governed in part by our want
of a steady support for the actions of our arms, and hands, as in threading
a needle, or hewing wood, or in swimming; when we are intent upon these
objects, we breathe at the intervals of the exertion of the pectoral
muscles.

2. The following natural animal actions are influenced by solar periods.
The periods of sleep and of waking depend much on the solar period, for we
are inclined to sleep at a certain hour, and to awake at a certain hour,
whether we have had more or less fatigue during the day, if within certain
limits; and are liable to wake at a certain hour, whether we went to bed
earlier or later, within certain limits. Hence it appears, that those who
complain of want of sleep, will be liable to sleep better or longer, if
they accustom themselves to go to rest, and to rise, at certain hours.

The periods of evacuating the bowels are generally connected with some part
of the solar day, as well as with the acrimony or distention occasioned by
the feces. Hence one method of correcting costiveness is by endeavouring to
establish a habit of evacuation at a certain hour of the day, as
recommended by Mr. Locke, which may be accomplished by using daily
voluntary efforts at those times, joined with the usual stimulus of the
material to be evacuated.

3. The following natural animal actions are connected with lunar periods.
1. The periods of female menstruation are connected with lunar periods to
great exactness, in some instances even to a few hours. These do not
commence or terminate at the full or change, or at any other particular
part of the lunation, but after they have commenced at any part of it, they
continue to recur at that part with great regularity, unless disturbed by
some violent circumstance, as explained in Sect. XXXII. No. 6. their return
is immediately caused by deficient venous absorption, which is owing to the
want of the stimulus, designed by nature, of amatorial copulation, or of
the growing fetus. When the catamenia returns sooner than the period of
lunation, it sho