; the motions of
the planets to attractive effluvia; and all the effects of the
comixture of the gases to benign or diabolical agency, as they
happened to produce on the parties good or evil. So in the like manner
old houses are generally said to be haunted, owing to the noises which
arise from the cracking and yielding of their walls and timbers, and
from the protection and easy passage which in the course of time they
afford to rats, mice, weasels, &c. whose activity in the night-time
affords the foundation of numerous apprehensions and fancies of the
credulous.

4. To spontaneous combustions or detonations, which produce occasional
lights and noises, or, under unchanged circumstances, recurring lights
and noises, chiefly claiming attention in the night. Thus houses shut
up and unaired are apt, from the putrefaction of animal and vegetable
matter, to generate hydrogen gas, the accidental combustion of which
by contact with phosphoric matter, naturally generated in the same
situation, will produce those effects of lights and noises heard in
empty houses. So Church-yards, Churches in which the dead are buried,
Cemeteries, and Ruins of old buildings, must frequently give out large
quantities of these gases; and consequently, from exactly similar
causes, they are likely to produce the very effects which we witness
in the will-o'-the-wisp, or in hydrogen gas when inflamed during calm
weather in marshy situations.

5. To the prevailing belief that effects, which cannot readily be
accounted for, or which are caused by the contact of the invisible
fluids or media always in action in the great laboratory of nature,
are produced by the agency of spirits or demons; which belief,
concurring with the unknown causes of the effects, and affording a
ready solution of difficulties, prevents further inquiry, silences
reasoning, and tends in consequence to sustain the prevailing errors
and superstitions.

Such are the general causes of ghosts, spirits, charms, miracles, and
supernatural appearances. They all arise either from hallucinations of
the mind or senses; from the mutual action of the natural, though
invisible, powers of gaseous and ethereal fluids; from the delusions
of ignorance, implicit faith, or the absence of all reasoning.

While occupied in these speculations, I arrived at the entrance of the
populous, industrious, and opulent village of Wandsworth. A reader in
the highlands of Scotland, in the mountains of Wales, o