Triple lens or Triunial magic lanterns were the iPhone 8 of their day.
Since the days of the Sturm lantern in the 17th century, the technology had developed from basic projectors producing small, dimly lit images, to these magnificent machines capable of spectacular technicolour lantern entertainments.
Its three lenses enabled a skilled lanternist to produce dissolving views – day seamlessly becoming night, silent volcanoes suddenly erupting – and moving picture effects. The height of this type of entertainment was reached in the 1880s when cast members were employed behind the scenes to providing sound effects for daily shows.