Webber worked as a miner in Loughor, Swansea and was introduced to spiritualism by his wife. He claimed his own mediumistic abilities such as levitation of objects, ectoplasm, psychokinesis and communicating with spirit voices. Webber claimed his spirit guides were 'Paddy' and 'Reuben'.
Webber was not scientifically tested by the Society for Psychical Research and some researchers have speculated that he performed his phenomena through trickery. During séances infrared flashlight photographs were taken of his phenomena which spiritualist writers have claimed is evidence for spirit communication, however, skeptics have written the ectoplasm in the photographs resembles cheesecloth or gauze.
According to the magician Julien Proskauer the floating trumpet of Webber was a trick. Close examination of photographs reveal Webber to be holding a telescopic reaching rod attached to the trumpet, and sitters in his séances only believed it to have levitated because the room was so dark they could not see the rod. Webber would cover the rod with crepe paper as ectoplasm to disguise its real construction. During the séances of Webber "spirit" voices were heard and the psychical researcher Hereward Carrington speculated that the voices were a trick performed by the medium himself by attaching a trumpet to the end of a telescopic reaching rod or a rubber tube.
The spiritual writer Harry Edwards supported the mediumship of Webber and included the photographs in his book The Mediumship of Jack Webber. The book was heavily criticized by the psychical researcher Michael Coleman who wrote "Edwards's book is essentially anecdotal, written from memory, often long after the events described. Thus we do not know where, when or for how long the individual sittings were held. We do not know how many sitters were present at each sitting, and we know the names of very few of them. But most importantly, we do not have those detailed sequences of events, with timings, that are necessary to arrive at a realistic assessment of any supposedly paranormal occurrences. Most of Edwards's account is unsupported by any independent witnesses".
- Jack Webber (1907–1940)
- Gaskill, Malcolm (2001). Hellish Nell: Last of Britain's Witches. Fourth Estate. p. 170.
- Harvey, John (2007). Photography and Spirit. Reaktion Books. p. 103.
- Stemman, Roy (2011). Spirit Communication: A Comprehensive Guide to the Extraordinary World of Mediums, Psychics and the Afterlife. Piatkus Books. p. 82.
- Taylor, John Gerald (1975). Superminds: An Enquiry Into The Paranormal. Macmillan. p. 142.
- Anderson, Roger (2006). Psychics, Sensitives And Somnambules: A Biographical Dictionary With Bibliographies. McFarland & Company. p. 182.
- Permutt, Cyril (1983). Beyond the Spectrum: A Survey of Supernormal Photography. HarperCollins Publishers. p. 62.
- Stein, Gordon (1996). The Encyclopedia of the Paranormal. Prometheus Books. p. 521.
- Proskauer, Julian (1946). The Dead Do Not Talk. Harper & Brothers. p. 94.
- Carrington, Hereward (1907). The Physical Phenomena of Spiritualism. Herbert B. Turner & Company. p. 201. "In the vast majority of cases, the trumpet talking is done by the medium himself. If the séance is in the dark, the medium’s task is an easy one, he having only to wave the trumpet about and imitate whatever voices he desires. By attaching a trumpet to the end of the telescopic rod... and moving this about, voices can be made to appear in various parts of the room at will. Sometimes the trumpet is partly in sight, when the room is only partially darkened, and yet the voices come. This is accomplished by a small piece of rubber tubing being attached to the mouth of the horn, and the medium speaks into the other end of this tube. The voice appears to issue from the horn. At other times the medium employs a second trumpet, speaking into that, and it is almost impossible to distinguish the difference by locating the sound. At other times the medium consents to be held by two sitters while the horn is doing the talking. When this is the case, the medium generally has a confederate, who manipulates the horn, does the talking, etc."
- Edwards, Harry (1978). The Mediumship of Jack Webber. The Harry Edwards Spiritual Healing Sanctuary.
- Coleman, Michael (1998). Letter to the Editor. Journal of the Society for Psychical Research. Volume 62: 372–374.