The general spread of metropolitan street lighting begins with the differential arc lamp, which is built in 1878 by Friedrich von Hefner-Alteneck, the chief designer at Siemens & Halske. The carbon rods between which the arc burns can be automatically readjusted and several lamps can be connected to a generator. The artificial grotto and the Moorish Kiosk at Linderhof Palace are also lit electrically with carbon arc lamps from 1878.