Key to Ghostism: Science and Art Unlock Its Mysteries by Thomas Mitchell, 1880.

"A spirit slate-writing experiment."  From Popular Mechanics, 1918.  This should be of interest: The Care & Feeding of a Spirit Board.

"I am introduced to my soul."  From A Man and His Soul, An Occult Romance by Theron Clark Crawford, 1894.

A spirit message written via a planchette: "'Aide-toi le ciel t'aidera' (Help yourself and Heaven will help you)."  From The Vanished Friend: Evidence, Theoretical and Practical, of the Survival of Human Identity After Death by Jules Thiébault, 1920.

An automatic drawing of the prince of peace rising out of the flames and smoke of worldly desires and ambitions.  From Spiritualism, Its Present-day Meaning by Huntly Carter, 1920.

Here a book on [so-called] scientific achievement is pitched as a spiritualist seance.  From an ad in Popular Mechanics, 1924.

"On the eve of the Nativity of St. John the Baptist, any person who, fasting, watches in the church porch, will see the spirits of those to die in the year to come knock at the door in the order in which they shall die."  From English Illustrated, 1895.

Spiritualists tipping a table, from "Spirit-Rapping Made Easy," in Once a Week, 1860.

We know what you're thinking, but this title isn't referring to how Twitter is mostly populated by bots.  It's actually about Ouija communications, automatic writing, and the like.  By Hester Travers Smith, 1919.

From "Spirit-Rapping Made Easy," in Once a Week, 1860.  This should be of interest: Seance Parlor Feng Shui.

"Another ghost photo."  From Popular Mechanics, 1908.

A spirit slate message from a ghost who'll be back in two hours.  From Medical Pickwick, 1921.

"A modern revival of devilism and sorcery."  From Satan, His Origin, Work, and Destiny by Carlyle B. Haynes, 1920.  This should be of interest: Seance Parlor Feng Shui.

"Scene illustrating spirit manifestation," from Satan, His Origin, Work, and Destiny by Carlyle B. Haynes, 1920.

"T'was contact with the dead."  From The Harvard Lampoon, 1921.

The Dead Have Never Died by Edward C. Randall, 1917.

"Casting out the evil spirits," plus the same scene in the ghostly realm (courtesy of the scanning process at Google Books), from The Rappers, Or, The Mysteries, Fallacies, and Absurdities of Spirit-rapping, Table-tipping, and Entrancement by A Searcher After Truth, 1854.

This recalls our repository of ghostly images that were never meant to be, entitled The Ghost in the [Scanning] Machine.  The specters were conjured unwittingly, through a mechanical process of book scanning.  Their portraits technically do not exist, except within this context.  To explain: in old books, frontispieces were typically protected by a sheet of translucent tissue paper.  So thorough is the Google Books scanning process that even this page of tissue paper is scanned.  The figure in the plate beneath the tissue—"beyond the veil,” as it were—emerges as from a foggy otherworld.  The frontispieces were never meant to be seen this way.  Their wraithlike manifestations have been artificially "fixed" in time by the scanning process. In essence, timeless phantasms of dead writers have been captured and bound into a new age.  And so we call this phenomenon "unforeseen art," as it constitutes an aesthetic expression without original intent.  Just as artists often credit their inspiration to a Muse, the accidental art herein is in the domain of real ghosts; every author here has departed to the Other Side.  We call it "necromancy by proxy," as the scanning machine serves as our "spirit medium" or shaman.