They supposedly were used in olden days to enable one to
see the present, the past and the future. They are of great
variety, and of great antiquity.
Varron claims that they are of Persian origin, the Magi
having used them for a method of divination called
Catoptromancy.
The persons who, in Rome, read these mirrors were called
Specularii.
In the East these instruments were called Stellar
Mirrors.
Pica della Mirandola had faith in them, provided they
were made under a favorable constellation, and that they
should only be consulted when one felt comfortably warm, for
the cold harms the lucidity of their oracle. Reinaud speaks
of them in his Description of the Blacas Cabinet. The
operators perfume them, fast for seven days before using
them, and recite sacramental prayers at the moment of
consulting them.
The Chinese and the Hindus made theirs of metal, concave
or convex.
Some bore the name of their inventor (Cagliostro,
Swedenborg, etc.)
More recently they have been used to fix the eye of
clairvoyants or mediums so as to put them into a state of
hypnosis.
Cahagnet, in his Magnetic Magic, quotes the principal
mirrors as follows:
The Theurgic Mirror - a bottle of clear water
looked at by a child and in which the Archangel Gabriel
replies by pictures to his questions.
The Mirror of the Sorcerers - any kind of mirror or pail of water. The country sorcerer, standing near the
consultant, recites a spell and shows him the reflection of the picture wanted.
The Mirror of Cagliostro - the bottle of clear
water is on a piece of furniture, and before it a child, on
whose head the operator places one hand and tells him the
questions to ask, to which replies are given in allegorical
pictures.
The Mirror of du Polet - a piece of cardboard
having pasted on one side a sheet of tin and on the other a
piece of black cloth. The operator magnetizes it strongly
and places it a foot away from the eye of the consultant
who, having fixed his eyes on it, soon sees in it the
desired object.
The Swedenborgian Mirror - a paste of graphite
mixed with olive oil is poured on an ordinary mirror and
allowed to dry for a few days. The consultant, whose image
must not be reflected (he stands at some distance for this
reason) looks into it, whilst the operator stares
magnetically at the back of his head, and vision takes
place.
The Magnetic Mirror - a round crystal globe filled
with magnetized water at which the consultant looks
carefully until the desired vision appears.
The Narcotic Mirror - similar globe but a narcotic
powder made of belladonna, henbane, mandragora, hemp, poppy,
etc., is dissolved in the water.
The Galvanic Mirror - it is made of two discs, one
of copper and concave, the other of zinc and convex, both
magnetized nine times in nine days. The center of the
concave is looked at.