This 1910's era arc lamp was intended for outdoor series circuit pole line street lighting. It employs a long consumable upper electrode rod which has a conductive an iron wire core. The rod is comprised of compressed magnetite (iron oxide), titanium dioxide, and chromite . The illuminating arc is formed when the top magnetite rod is struck against a small button made of stacked copper plaited steel washers mounted in the lower electrode holder. These lamps were used on 4 amp DC constant current circuits.

Westinghouse lamps of this design were in use in a few cities cir. 1908-1925 primarily in Pittsburgh and Denver. They never gained the popularity of the the competing General Electric magnetite lamp known as the "Luminous Arc Lamp" [id=618976274] of which many tens of thousands were produced. These lamps were commonly hung from wood utility poles on long mast arms. Very few of these unique pole line street lighting fixtures still exist. [id=677213724] to see a historic 1922 photograph of this specific type of lamp in service in Pittsburgh . The lamp in this picture was historically used in Pittsburgh It has been restored to full operable condition. Unfortunately it contains the only surviving unused new old stock arc electrode set for this lamp design currently known to exist and there are no known surviving spare electrodes for this lamp. I have decided therefor not to attempt to energize the lamp unless some spare replacement electrodes can be located. The electrode set would normally be consumed after about ~130 hours of operation. Here is a view of the internal mechanism of this lamp[id=677255844] .

General Electric and Westinghouse were the only North American manufacturers that developed and produced magnetite lamps. Each manufacturer produced a unique patented proprietary design. The consumable electrodes for these lamps were proprietary products of each respective manufacturer. I have never located an old stock supply of replacement electrodes for ether type of lamp although I have experimented with making reproduction replacement electrodes for the GE lamps.