Baird 10" mirror drum with 20 mirrors, 1937-1938.

This 20-facet mirror drum was used in Baird's colour television camera and/or projector used at the Dominion Theatre demonstrations in December 1937 and February 1938. It was designed by John Logie Baird and his assistant, Paul Reveley; constructed by B J Lynes Limited. It was driven at 6,000 r.p.m. by a 100 Hz synchronous motor. It had to be enclosed to reduce air turbulence to an acceptable level. In this colour system, images were interlaced six times and a large screen colour picture with 120 lines was produced.