Created during the Spiritualism movement, book tests are experiments to exclude the working of telepathy in mediumistic communications. In answer to questions or for reasons of personal relevance the communicator indicates a certain book upon a certain shelf in the home of the sitter and gives the text on a certain page. In such experiments far more successes were registered than chance would justify. The books selected are usually those of which the communicator was fond in his lifetime, thus offering another suggestion of personal identity. Many excellent cases of book tests are recorded in Lady Glenconner's The Earthen Vessel and in Some New Evidence for Human Survival, 1922, by the Rev. Drayton Thomas. Sir William Barrett, in his preface to this book, quotes the following communication which purported to come from Myers to him: "There were some books on the right-hand side of a room upstairs in your house in Devonshire Place. On the second shelf, four feet from the ground, in the fourth book counting from the left, at the top of page 78, are some words which you should take as direct answer from him (Myers) to so much of the work you have been doing since he passed over." Asked if the name of the book could be given, the reply was - "No," but that whilst feeling on the cover of the book he got a sense of "progression." Two or three books from this test book are one or two books on matters in which Sir William used to be very interested, but not of late years. It is connected with studies of his youth."

Professor Barrett remarks that Mrs. Leonard, the medium of the communication, never visited his house. He had no idea what books were referred to, but on returning home found that in the exact position indicated, the test book was George Eliot's Middlemarch. On the first line at the top of page 78 were the words .. "Ay, ay. I remember-you'll see I've remembered 'em all" which quotation was singularly appropriate, as much of his work since Mr. Myers passed over has been concerned with the question of survival after death and whether the memories of friends on earth continued with the discarnate. But the most remarkable part of the test was yet to be discovered. In dusting the bookshelves the maidservant, unknown to the Professor, had replaced two of George Eliot's novels by two volumes of Dr. Tyndall's books, viz., his Heat and Sound, which were found exactly in the position indicated. In his youth Prof. Barrett was, for some years, assistant to Prof. Tyndall, and these books were written whilst he was with him.

By what process is the discarnate intelligence able to find a relevant passage in closed books? One of the preliminary statements which the Rev. Drayton Thomas received from his father was that he "sensed the appropriate spirit of the passage rather than the letters composing it." After eighteen months he appeared to acquire a power of occasionally seeing the words by some sort of clairvoyance. The giving of the page is one of the greatest difficulties. The impression left on the Rev. Drayton Thomas'mind was that when a page had been fixed upon as containing a thought suitable for the test, the operator counted the pages between that and the commencement. He usually starts where the flow of thought commences and when it ceases and recommences higher up he concludes that he passed from the bottom of one page to the top of another. In this way, they say, it is found practicable to compute the number of pages between the commencement and the passage fixed upon for the test. When verifying, one usually counts from the commencement of the printed matter, disregarding fly-leaves and the printer's numbering.

The experiments were just as successful when a sealed book, deposited by a friend in the Rev. Drayton Thomas' house, was used; with an unseen bookshelf; with a parcel in which an antiquarian at random packed in some books and which was unopened; and with books placed in the dark in an iron deed-box. If these results are to be explained by the medium's supernormal powers, she has to be endowed, as the Rev. Drayton Thomas points out, with such a degree of clairvoyance as would permit the making of minute observations in distant places and retaining a memory of things there seen, with ability to extract the general meaning from printed pages in distant houses, despite the fact that the books concerned are not open at the time, with ability to obtain knowledge of happenings in the sitter's home and private life relating both to the present and to the distant past and with an intelligence which knows how to select from among our host of memories the suitable items for association with the book-passage, or conversely, of finding a suitable passage for the particular memory fished from the depths of our mind. His own conclusion was that the book tests were obtained by a spirit who gleaned impressions psychometrically and obtained an exact glimpse now and again by clairvoyance.

The underlying idea of book tests goes back to the experiments of Sir William Crookes. A lady was writing automatically with the planchette and he tried to devise a means for the exclusion of "unconscious cerebration." He asked the invisible intelligence if he could see the contents of the room, and on receiving an affirmative answer he put his finger on a copy of The Times which was on a table behind him, without looking at it, and asked that the communicator should write down the word which was covered by his finger. The planchette wrote the word "However." He turned round and saw that this was the word covered by the tip of his finger. This experiment was first published in January, 1874, in the Quarterly Yournal of Science.

The first plain book tests were recorded by Stainton Moses. He wrote automatically, under the dictation of Rector: "Go to the book case and take the last book but one on the second shelf, look at the last paragraph on page 94, and you will find this sentence. . . ." The sentence was found as indicated. The experiment was repeated a number of times.

Of other mediums William Eglinton was particularly successful in direct-writing book-tests. Many cases are described in John S. Farmer's Twixt Two Worlds. The page and line were selected by tossing coins and reading the last numbers of the dates. In some cases they were still further complicated by prescribing the use of colored chalk in a set order of the words. Book tests combined with xenoglossis are described in judge Ludwig Dahl's We Are Here, published in 1931. The Norwegian judge writes of the mediumship of his daughter, Ingeborg, and describes how her two (deceased) brothers "were represented as going into another room and reading aloud passages from a book still on the shelves, the number of which was selected by one of the sitters-the medium successfully repeating or transmitting what they read in a foreign language and far beyond her comprehension."

Mrs. Henry Sidgwick, in her study of the problem of book tests in Proceedings S.P.R., April, 1921, arrives at the conclusion: "On the whole, I think, the evidence before us does constitute a reasonable prima facie case for belief in the perception of external things not known to any one present, but known to someone somewhere."