An energy held supposedly capable of stimulating the activity of the psychic senses. In 1948, Dutch researcher N. Zwaan demonstrated an apparatus, which supposedly created the Zwaan rays, at a gathering of the International Spiritualist Federation Congress in London. The following year, the Spirit Communication Society was founded in Manchester, England, at which time an improved Zwaan-ray machine was demonstrated, and in 1954 an optimistic report was issued. However, the Zwaan rays were never shown as having more than subjective effects upon people who already believed in them, and the Zwaan apparatus in subsequent years was abandoned