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Unsigned, attributed to Nicholas Callan, 1837
In his records, Callan wrote about the instrument he devised that “it was the first contact-breaker ever made”. The purpose of the design was to produce rapid succession of electrical currents in the coil by rapidly making and breaking communications with the battery. Using this instrument allowed Callan to achieve more than fifty interruptions per second.
The Callan Repeater was one of the models 3D printed for the project: