Glass insulators were apart of the electric transmission system that powered telegraphs, telephones and locomotives during the mid to late 19th century. Pintypes, such as the one above, were grooved at the base to support wire conductors and drilled underneath to be placed on top of spiked poles. Threadless insulators had trouble staying in place on utility poles and were later replaced with threaded pintypes.
The mark “Canadian Pacific RY CO” (Canadian Pacific Railway Company) built their railways beginning in 1880s, approximately 10-15 years after threadless insulators were phased out. Based on the threadless design of this insulator, the power lines may have been installed several years before the railways were actually completed.
Sources:
McDougald , J. & C. McDougald. "Insulators: a history and guide to north american glass pin type insulators" Online, 1990.