English: Two wires e e, which are connected with the mercury tubes f, are attached to the metal springs c, which are the carbon holders. These springs are regulated by the slide d consisting of insulating material. The tubes f and h pass through an india-rubber cork g; i is a layer of mercury, and over it is a layer of cement j. The glass vessel is exhausted by means of the tube h. Lane-Fox prepared the carbon filaments for his lamps in the following manner: Hemp threads were wound round a piece of coke having a knife-edge at one side; and the whole placed in an oven. During carbonisation the threads contracted and were cut by the knife-edge. In this manner carbons of the same length were obtained. Benzole, or similar vapour, was used for carbonising the filaments, whilst the carbons were made white-hot by means of electric current. The ends of the filaments were connected with a short piece of wire (short-circuited), and again a current passed through them. The lamp was constructed in different sizes and, for example, for an intensity of 87 candles, 66 volts and 0.673 ampere were required.