I picked up some these curiosities in a car boot sale, no known history. Anyone have any info , particularly date.
They are made of 2 sandwiched very thick 1/8 inch glass slabs with obvious epoxied over liquid filler-holes, otherwise size etc is much the same as modern, standard sloping 7 segment displays, conductive lands and traces etc. These ones 3 1/2 digit and annunciators for DVM. No built in polarizers. The segments go cloudy white on 40 to 60V ac drive, the same between added polarizers. Wrapped in tissue paper, then expanded polystyrene and original cardboard wrapping , new unused, made by Hamlin Inc, type number 3601-0