Details
A similar card disc with double spiral
of twenty holes, inscribed in pencil, probably in Baird's hand 14" 20 Line Double Spiral Holes ½0" -- 14 in. (35.5 cm) diam., centre hole 3/16 in. (4.5 mm.) approx.
of twenty holes, inscribed in pencil, probably in Baird's hand 14" 20 Line Double Spiral Holes ½0" -- 14 in. (35.5 cm) diam., centre hole 3/16 in. (4.5 mm.) approx.