Edison lamp with mechanical vice filament clamps likely of platinum or nickel with later "plaster collar" base. Filament of carbonized bamboo. Lamp likely produced in the latter part of 1880, but based c. November of 1881. Notes contained in The Edison Papers Vol 6. (citation to be added) show communication between Edison, Francis Upton, and Charles Batchelor discussing the new base design. Upton mentions that the new base allows for a larger diameter neck, allowing use of older batches of lamps that would not fit the previous ("Johnson Bevel Ring" style) base.
