e, the
superabundance of this sensorial power actuates and invigorates the whole
moving system, giving strength and frequency to the pulse, and an universal
glow both of colour and of heat, as in violent anger, or outrageous
insanities.

If, in the feverish sleep above described, the skin becomes cooled by the
evaporation of much perspirable matter, or by the application of cooler
air, or thinner clothes, the actions of the cutaneous capillaries are
lessened by defect of the stimulus of heat, which counteracts the increase
of sensibility during sleep, and the pulsations of the heart and arteries
become slower from the lessened stimulus of the particles of blood thus
cooled in the cutaneous and pulmonary vessels. Hence the admission of cold
air, or ablution with subtepid or with cold water, in fevers with hot skin,
whether they be attended with arterial strength, or arterial debility,
renders the pulse slower; in the former case by diminishing the stimulus of
the blood, and in the latter by lessening the expenditure of sensorial
power. See Suppl. I. 8. and 15.

13. _Incubus._ The night-mare is an imperfect sleep, where the desire of
locomotion is vehement, but the muscles do not obey the will; it is
attended with great uneasiness, a sense of suffocation, and frequently with
fear. It is caused by violent fatigue, or drunkenness, or indigestible
food, or lying on the back, or perhaps from many other kinds of uneasiness
in our sleep, which may originate either from the body or mind.

Now as the action of respiration is partly voluntary, this complaint may be
owing to the irritability of the system being too small to carry on the
circulation of the blood through the lungs during sleep, when the voluntary
power is suspended. Whence the blood may accumulate in them, and a painful
oppression supervene; as in some haemorrhages of the lungs, which occur
during sleep; and in patients much debilitated by fevers. See Somnus
interruptus, Class I. 2. 1. 3. and I. 2. 1. 9.

Great fatigue with a full supper and much wine, I have been well informed
by one patient, always produced this disease in himself to a great degree.
Now the general irritability of the system is much decreased by fatigue, as
it exhausts the sensorial power; and secondly, too much wine and
stimulating food will again diminish the irritability of some parts of the
system, by employing a part of the sensorial power, which is already too
small, in digesting a great q