(Photograph courtesy of Durward Center)

Figure 5. This primitive design for playing paper music rolls used an inverted tracker bar that contacted the top of the moving paper roll. Beneath the tracker bar and paper was another bar with one long slit connected to the wind pressure supply. A perforation in the roll would allow wind to pass into a tracker bar port which was then conducted to a specific pneumatic that opened a valve and caused a pipe to speak. There are no known Welte instruments extant that made of this design or anything similar to it.

(Photograph courtesy of Durward Center)

Figure 6. The pneumatic mechanism shown in the Welte patent of 1889 changed little over the course of production. This system required both a pressure and a vacuum supply, which became standard for Welte orchestrions. These new pneumatic machines could still be ordered powered by weight driven clockwork motors as could the earlier pinned cylinder machines, but also, an option of electric or water motor was now offered.