Pittsburg porcelain signals
   The Pittsburg High Voltage Insulator Co. located in Deary, Pa, began prodution in 1908 and seems to have ended sometime in 1921-1922.
U-243
Incised on dome JUN 10 A.M.
U-243
Hard to make out in pic but incuse marking on dome reads "MAY # # P. M."
similar to a U-293
Hard to make out here but incised on dome and reads AUG 21 PAID
U-344A MLOD
Incised on dome "FEB 01"