are much exhausted by their efforts
to proceed on their journey, as well as benumbed by cold. And as much
greater exercise can be borne without fatigue in cold weather than in warm;
because the excessive motions of the cutaneous vessels are thus prevented,
and the consequent waste of sensorial power; it may be inferred, that the
fatigued traveller becomes paralytic from violent exertion as well as by
the application of cold.

Great degrees of cold affect the motions of those vessels most, which have
been generally excited into action by irritation; for when the feet are
much benumbed by cold, and painful, and at the same time almost insensible
to the touch of external objects, the voluntary muscles retain their
motions, and we continue to walk on; the same happens to the fingers of
children in throwing snow-balls, the voluntary motions of the muscles
continue, though those of the cutaneous vessels are benumbed into
inactivity.

Mr. Thompson, an elderly gentleman of Shrewsbury, was seized with
hemiplegia in the cold bath; which I suppose might be owing to some great
energy of exertion, as much as to the coldness of the water. As in the
instance given of Mr. Nairn, who, by the exertion to save his relation,
perished himself. See Sect. XXXIV. 1. 7.

Whence I conclude, that though heat is a fluid necessary to muscular
motion, both perhaps by its stimulus, and by its keeping the minute
component parts of the ultimate fibrils of the muscles or organs of sense
at a proper distance from each other; yet that paralysis, properly so
called, is the consequence of exhaustion of sensorial power by exertion.
And that the accumulations of it during the torpor of the cutaneous vessels
by exposure to cold, or of some internal viscus in the cold fits of agues,
are frequently instrumental in recovering the use of paralytic limbs, or of
the motions of other paralytic parts of the system. See Spec. 4. of this
genus.

Animal bodies resist the power of cold probably by their exertions in
consequence of the pain of cold, see Botan. Gard. V. 1. additional note
xii. But if these increased exertions be too violent, so as to exhaust the
sensorial power in producing unnecessary motions, the animal will probably
sooner perish. Thus a moderate quantity of wine or spirit repeated at
proper intervals of time might be of service to those, who are long exposed
to excessive cold, both by increasing the action of the capillary vessels,
and thus produci