Episodes of high comedy in the history of science are rare, but here is one: the investigation of Eusapia Palladino, a tempestuous and erotically charged medium from the slums of Naples, by a sober Cambridge don and his friends in 1895.

The Cambridge group was from Britain's Society for Psychical Research, and they trained themselves hard for the task. Their leader, Henry Sidgwick, was a prominent moral philosopher; his wife, Nora (the sister of a future British prime minister), was a mathematician and the principal of one of Cambridge's first colleges for women. Together the couple practiced how they would hold Eusapia down during seances. As Deborah Blum writes in her fascinating new book, Ghost Hunters, Sidgwick developed an impressive skill for "dropping to the floor, his white beard trailing over the carpet, while he anchored Nora's feet in place."

Eusapia's apparent ability to levitate heavy tables, make mysterious winds blow and produce a substance known as "ectoplasm" - a sort of afterbirth of the netherworld - had already convinced some scientists in Europe that paranormal powers were real. But she had been married to a traveling conjuror and would be caught in trickery countless times. Members of the Society for Psychical Research wanted to be sure. But above all, they wanted to believe. If Eusapia was exposed, they would find someone with more impressive powers. Blum's strange tale shows how and why many British and American intellectuals (including some prominent scientists) ended up on a fruitless but determined hunt for ghosts.

Blum, a professor of science journalism at the University of Wisconsin, begins in America in the middle of the 19th century. In 1848, the Fox sisters, a pair of teenage girls from upstate New York, demonstrated their skill at eliciting information from spirits at P.T. Barnum's museum on Broadway. The Night Side of Nature, a collection of ghost stories presented as fact, became a best seller. The spiritualist newspapers, of which there were many, claimed two million believers. Table-tilting and spirit-writing were all the rage. By the 1880's, Sears, Roebuck and other companies were mass-marketing Ouija boards. America itself, Blum writes, "seemed possessed."

Meanwhile in England, Alfred Russel Wallace, the co-presenter of the idea of natural selection with Darwin in 1858, had started visiting mediums and was mightily impressed. He was particularly taken with Daniel Dunglas Home, whose powers, according to astonished witnesses, included the ability to levitate, float out of a window and then float back in. Home, who became one of the best-known mediums in Europe, also floated into high society, marrying a goddaughter of the czar, with the novelist Alexandre Dumas as his best man.

Darwin was exasperated by Wallace's gullibility and feared that his activities would somehow besmirch the theory of evolution. Wallace, however, suspected that evolution explained only the origins of bodies, and that a supernatural "overruling intelligence" was required to explain mental and moral life. Most of the scientific establishment, on both sides of the Atlantic, disagreed - often vehemently, as in the case of the scientist and lecturer T.H. Huxley, known as "Darwin's bulldog" - and asserted that spiritualism was pure trickery that needed exposing rather explaining. But a smattering of eminent scientists remained open-minded or even joined the cause.

Wallace brought the chemist William Crookes, future president of the British Association for the Advancement of Science, into the fold. Crookes was the discoverer of thallium - a toxic element that some skeptics alleged had adversely affected his mind - and his work on cathode rays played a role in the discovery of the electron. Not only was Crookes convinced by Home, he was enchanted by Florence Cook, a strikingly pretty girl in her early 20's who liked to conduct her seances in tight black dresses. While Florence was locked in her spirit cabinet, her "spirit guide" would materialize in flowing, white robes and eat cakes and drink wine while she flirted with Crookes.

Even mediums complained of the fraud that was rife in their trade. So in 1882, Sidgwick and his friends formed the Society for Psychical Research with the earnest intention of investigating supernatural claims. Sidgwick, the son of a clergyman, had abandoned Christianity but feared the moral effects of the decline of religion. His co-founders included his pupil Frederic Myers, another disillusioned clergyman's son whose interest in spiritualism would markedly increase after his beloved drowned in a lake, and the Cambridge scholar Edmund Gurney, described as having "a mind as beautiful as his face" by George Eliot, who supposedly based Daniel Deronda in part on him. All three men accepted the dominion of modern science; their aim was to imitate its methods and provide rigorous, empirical evidence of a spiritual realm.

This idea, or something like it, evidently appealed to many intellectuals of the day, including Tennyson (who was Britain's poet laureate at the time), Leslie Stephen (the father of Virginia Woolf), John Ruskin, Lewis Carroll and Mark Twain, who were all members of the Society for Psychical Research. It also seized the interest of William James, who served as president of the British society for two years and was involved with the short-lived American version. (Blum's subtitle is misleading: James is not the main focus of this book.) As America's pioneer in psychology, he was intrigued by the apparently extraordinary powers of mediums' minds. But he was also drawn to the evidence they seemed to provide for his belief in "a continuum of cosmic consciousness against which our individuality builds but accidental fences." In 1885, shortly after the death of his 1-year-old son, he visited a Boston psychic named Leonora Piper at the suggestion of his mother-in-law. Although he never quite accepted that life after death had been proved, James was soon convinced that Mrs. Piper (who died in 1950, at 93) knew things she could only have discovered by supernatural means. Like many other investigators, James was prepared to rest his case solely on her startling abilities.

Blum tells her literally wondrous tale very well. But apart from the vague suggestion that it answered a need created by the encroachment of science on religious belief, she offers very little reflection on the question of why spiritualism suddenly became so popular. And perhaps she tells her tale too even-handedly, since readers may be left with the impression that the Society for Psychical Research was on to something. The book is peppered with narratives reporting ghost stories and seances. Blum writes that these are "derived from" documents, often from the society's archives, although the telling of them is her own. But these narratives obscure the methods that mediums like Mrs. Piper used - methods that have been explained by debunkers like Martin Gardner, who in 1992 published a long exposé called "How Mrs. Piper Bamboozled William James." For example, Blum's ghost narratives do not show, as Gardner did, how Mrs. Piper fished for information by gauging her sitters' responses to all her wrong answers, or mined the information available from earlier sittings, from sittings with others and from things said while her sitters believed she was unconscious in a trance.

Despite the meticulous and often Herculean efforts of the society, more than a century of psychical research has added nothing to the stock of human knowledge. There is today no more reason to believe in spiritualism or telepathy than there was in the Victorian era, when the bearded men of science groveled earnestly at the feet of dubious mediums. Of course, parapsychology's hosts of remaining enthusiasts will vehemently disagree. But, to avoid swamping the mail slots and in-boxes of the Book Review, readers should send messages about this by psychic means only, please.

Anthony Gottlieb is the author of "The Dream of Reason: A History of Philosophy From the Greeks to the Renaissance." He is currently writing a book about the idea of nothingness.