produced various models of nickelodeons, such as the early Wurlitzer Mandolin Quartette – Wurlitzer's alternative to the Regina Sublima Piano. This machine has a reiterating piano with mandolin attachment along with an accompanying piano. They later introduced the Wurlitzer A.P.P. roll; a universal roll to be used on all subsequent Wurlitzer nickelodeons. Models such as the B(X), C(X), D(X) and I(X) use this roll. Wurlitzer also produced an automatic roll changer system so when a roll finished rewinding another was put on in a carousel-like system. An 'X' at the end of a model number indicates that model was fitted with a roll changer. Records indicate Wurlitzer sold player piano mechanisms to other manufacturers who installed Wurlitzer components in their own pianos and sold them under other brand names. One example is the Milner player piano company. Milner pianos were built in Cincinnati at a time consistent with Wurlitzer's presence there. Company records suggest Wurlitzer acquired the Milner company in addition to the several other companies acquired by Wurlitzer over the years, but it is possible that Milner may have simply used Wurlitzer components in their own product. Theatre organs Perhaps the most famous instruments Wurlitzer built were its pipe organs (from 1914 until 1943), which were installed in theatres, homes, churches, and other venues. These were marketed as The Mighty Wurlitzers. Englishman Robert Hope-Jones, considered the inventor of the theatre organ, had developed a concept of the organ as a "one man orchestra" to accompany silent movies. Hope-Jones's concept was based on two principles: That a pipe organ should be able to imitate the instruments of an orchestra That the console should be detachable from the organ. Among his sound innovations were a kind of electro-pneumatic action, the Diaphone and the modern Tibia Clausa with its strong 8′ flute tone. The Tibia Clausa eventually became a staple of theater organs. Hope-Jones organs were also noted for such innovations as stopkeys instead of drawknobs and very high wind pressures of 10″–50″ to imitate orchestral instruments. He also used a system of unification, which multiplied considerably the number of stops relative to the number of ranks. Between 1887 and 1911 his company employed 112 workers at its peak, producing 246 organs. But shortly after merging his organ business with Wurlitzer, he committed suicide in 1914 in Rochester, New York, frustrated by his new association with the Wurlitzer company, it is said.