As early as 1922, Charles F. Jones, partner in San Francisco-based Colorco and later Tricolor, received his patent (US no. 1416645) for a Duplex camera which was designed to take 'at a single exposure a plurality of negatives taken from the same point of view...and wherein there is provided an improved mechanism for intermittently moving the film, enabling duplicate registry of negatives...' This invention facilitated the bi-pack running of film which was central to many of the experiments with colour-separation processes including the ultimately successful three-strip Technicolor system. The present camera would appear to represent the mid-way stage in Tricolor's development of color-separation cinematography and is the most distinctive design, having the magazines set perpendicularly to each other rather than in parallel. The design accommodates a beam-splitting prism (no longer present) which would have separated the white light into its constituent parts to provide separate cinematographic records.