Perhaps the best claimant to successful mediumship was Mrs. Leonora E. Piper of Boston, Massachusetts.  Her mediumship began spontaneously in 1884, on the occasion of  going into a trance during the seance of  another medium . At first her controlling spirits rather pretentiously claimed to be Bach and Longfellow.  Then appeared a self-styled French doctor who gave the name of  Phenuit and spoke in a gruff male voice full of  Frenchisms, Negro patois, and vulgar Yankee slang, nevertheless offering successful diagnoses and prescriptions.  Often the deceased relatives of  the sitters would speak through Mrs. Piper at her seances.

In 1886 William James, the great American psychologist, anonymously attended one of  her seances.  He was sufficiently impressed with the information that she revealed to him he sent some 25 other people, using pseudonyms, to her.  Fifteen of these people reported back to James that they had received from her names and facts it was improbable she should know.  In 1886, James issued a report to the SPR:

My own conviction is not evidence, but it seems fitting to record it.  I am persuaded of  the medium's honesty, and of  the genuineness of  her trance;  and although at first disposed to think that the  "hits"  she made were either lucky coincidences, or the result of knowledge on her part of  who the sitter was and of  his or her family affairs, I now believe her to be in the possession of  a power as yet unexplained.
Despite his interest in Mrs. Piper, William James gave up the inquiry at this point. Having convinced himself of  her validity, he chose to give his other work higher priority at that time.  The following year, however, Richard Hodgson, who had gained a reputation as a skeptical researcher for his debunking of  Madame Blavatsky, arrived in Boston to head the American branch of  the SPR.   He was astounded when Mrs. Piper was able to offer many details about his family in Australia.  To check on her honesty, he even had her and her family shadowed for some weeks by detectives.  James and Hodgson decided it would be wise to test Mrs. Piper in another environment, where she would have neither friends nor accomplices to aid her.  Accordingly she was invited to England by the SPR organization and set off  in November 1889.

The results with Mrs. Piper in England were mixed.  On a good day she was able to produce a mass of  detailed information about the sitters which generally left them dumbfounded.  On a bad day, her control, Phenuit, would behave in a most obnoxious manner, keeping up a constant babble of  false assertions and inane conversation, blatantly fishing for information, and generally provoking the sitters. On no occasions was it concluded that Phenuit was anything more than a secondary personality of  Mrs. Piper's.

During one seance Mrs. Piper revealed to Sir Oliver Lodge a great deal of information regarding an uncle of  his who had been dead for twenty years.  Lodge sent an agent to inquire in the neighborhood where the uncle had lived.  In three days he was unable to unearth as much information as Mrs. Piper had provided.  All of  her remarks were eventually verified by surviving relatives.

In 1890 Mrs. Piper returned to the United States where she worked very closely with Richard Hodgson who spent the following fifteen years investigating her mediumship.
 
Psychiatrist Nandor Fodor gives us a picture of  Hodgson's research with
Mrs. Piper:

His first report on the Piper phenomena was published in 1892.... In it no definite conclusions are announced.  Yet, at this time Hodgson had obtained conclusive evidence.  But it was of  a private character and as he did not include the incident in question in his report, he did not consider it fair to point out its import.  As told by Hereward Carrington in The Story of  Psychic Science, Hodgson when still a young man in Australia had fallen in love with a girl and wished to marry her . Her parents objected on religious grounds.  Hodgson left for England and never married.  One day, in a sitting with Mrs. Piper, the girl suddenly communicated, informing Dr. Hodgson that she had died shortly before.  This incident, the truth of  which was verified, made a deep impression on his mind.

At first Hodgson felt that Mrs. Piper's knowledge came to her telepathically. However, during a sitting in March of  1892 a new controlling spirit came who identified himself as a George Pellew, a prominent young man who had been killed a few weeks earlier and who was casually known to Hodgson.  Five years previously he had had one anonymous sitting with Mr Piper.  Pellew eventually replaced Phenuit as the main control and as the intermediary between the sitters and the spirits of  their deceased friends.  This particular control was very realistic and seemed to Hodgson to be more than a mere secondary personality.  He showed an intimate knowledge of  the affairs of  the actual George Pellew, by recognizing and commenting on objects that had belonged to him.  Out of  150 sitters who had been introduced to him he recognized exactly those thirty people with whom the living Pellew had been acquainted.  He even modified the topics and style of conversation with each of these friends, and showed a remarkable knowledge of  their concerns. Very rarely did the Pellew personality slip up.

Mrs. Piper had never once in her career as a medium been detected in a dishonest action.  Frank Podmore, the severest critic in the SPR, became convinced of  the genuineness of  her telepathic phenomena and, based on the Pellew material, the skeptical Richard Hodgson was inclined toward a spiritualistic position.

To credit spiritualism, he based his arguments for this position largely on the fact that a good amount of  verified evidence Pellew produced was unknown to anyone in the room at that time, and therefore could not have been picked up telepathically by any of  the sitters.

In 1897, Hodgson published a report on Mrs. Piper in the Proceedings of  the Society for Psychical Research:

At the present time I cannot profess to have any doubt that the chief  communicators to whom I have referred in the foregoing pages are veritably the personages that they claim to be, and that they have survived the change that we call death, and that they have directly communicated with us whom we call living, through Mrs. Piper's entranced organism.

Mrs. Sidgewick argued against this position, emphasizing the occasions that the personality of  the control did seem to degenerate.

Eventually several other spirits seemed to take control over Mrs. Piper's mediumship including that of  the departed Reverend Stainton Moses. 

In the presence of  William James, America's foremost psychologist, the  "Hodgson control"  was able to describe incidents that Hodgson and James had intimately experienced together in life and were unknown to other individuals.  The personality was quite clear and distinct.  At other times this was not the case and the  "spirit" seemed like an obvious personation from Mrs. Piper's mind.  In analyzing this data, James suggested several factors were at play:

Extraneous  "wills to communicate"  may contribute to the results as well as a  "will to personate,"  and the two kinds of  will may be distinct in entity, though capable of helping each other out.  The will to communicate, in our present instance, would be, on a prima facie view of  it, the will of  Hodgson's surviving spirit; and a natural way of  representing the process would be to suppose the spirit to have found that by pressing, so to speak, against  "the light,"  it can make fragmentary gleams and flashes of  what it wishes to say mix with the rubbish of  the trance-talk on this side. The two wills might thus strike up a sort of  partnership and reinforce each other.  It might even be that the  "will to personate"  would be comparatively inert unless it were aroused to activity by the other will.  We might imagine the relationship to be analogous to that of  two physical bodies, from neither of  which, when alone, mechanical, electrical or thermal activity can proceed.  But, if the other body be present, and show a difference of  `potential, action starts up and goes on apace.
I myself feel as if  an external will to communicate were probably there - that is, I find myself doubting, in consequence of  my whole acquaintance with that sphere of phenomena, that Mrs. Piper's dream-life, even if  equipped with telepathic powers, accounts for all the results found.  But if  asked whether the will to communicate be Hodgson's, or be some mere spirit counterfeit of  Hodgson, I remain uncertain and await more facts, facts which may not point clearly to a conclusion for fifty or a hundred years.

While James affirmed his belief in the reality of  the Hodgson spirit, based on his sense of  dramatic probabilities, he acknowledged the case was not a good one because Hodgson had known Mrs. Piper so well in life.  There was no way of proving any of  the evidential material did not simply come from her unconscious
mind.

BACK