Section 45. A company may, for all purposes necessary or reasonably incident to the construction, maintenance or operation of its railway, generate, manufacture, use and transmit electricity in any city or town where authorized to operate its railway, and may erect and maintain therefore, as a part of its railway, and subject to sections seven, seventy, seventy-one and seventy-seven, relative to the grant and revocation of authority therefor, poles and trolley, feed and stay wires, and other proper devices for, or used in connection with, the transmission of electricity, of materials and workmanship prescribed in the grant of authority therefor, in, over and under any ways and bridges in any such city or town; provided, that authority to erect and maintain the same is granted by the board of aldermen of the city or selectmen of the town, respectively; and may also erect and maintain such poles, wires and other devices upon and over any private land, with the consent of the owners thereof.