Brown insulator with round top used on a telegraph pole on former County Donegal Railway.
1870 telegraph insulator from England in a Salt Glaze U-1364 includes mark: "8 Varley's Patent".
These were uniquely made with threads but designed to help the cement hold firmly to the inner cup. The inner cup according to the patent drawings in Keith Neal's book are threadless- the pin was always cemented into the inner cup. So, this is a unique style insulator that was made during the transition period of strict threadless to threaded pin-type insulators.