The Rapieff burner, employed in the 'Times' office, consists of four carbon pencils, arranged thus [Symbol] (except that the two v's are not in the same plane, but in planes at right angles to each other). The spark crosses the space between the points of the v's, and arrangements are made for keeping the two points at the right distance from each other, and also for keeping the ends of the two pencils which form each point in their proper position. If the current is from any cause interrupted, an automatic arrangement is adopted to allow the current to pass to the other lamps in the same circuit. There are six lamps in circuit at the 'Times' office; and M. Rapieff has exhibited as many as ten. The advantages claimed for this light are the following:--'First, its production by any description of dynamo-electric machine with either alternating or continuous currents; secondly, great diversibility and complete independence of the several lights, and long duration without change of carbons; and lastly, the extreme facility with which any ordinary workman or servant can renew the carbons when necessary, without extinguishing the lights.' The last-named advantage results, it need hardly perhaps be said, from the use of two carbons to form each point. One can be removed, the other remaining to keep the voltaic arc intact until a new carbon has been substituted for its fellow; then it in turn can be replaced by a new carbon, the new carbon already inserted keeping the voltaic arc intact. The six lamps at the 'Times' office thoroughly illuminate the room, and give light for working the eight Walter presses used in printing the paper. The light has been thus used since the middle of last October, and it is said that other rooms in the building are shortly to be illuminated in the same manner. 'Each lamp is enclosed in an opal globe of about four inches in diameter, and so little heat is given off, that the hand can be placed on the globe without inconvenience, even after the light has been burning for some time.' In the Wallace lamp there are two horizontal plates of carbon, about nine inches in diameter, instead of mere carbon points. When the current is passing, these carbon plates are separated by a suitable small distance which remains unchanged. The electric arc, being started at the point along the edge of the carbons where there is least resistance to the passage of the current, gradually passes along the edge of the carbons as combustion goes on, changing the position of the place of nearest approach and consequently of least resistance. The light will thus burn for many hours (even for a hundred with large carbon plates), and any number of lights up to ten can be worked from the machine. The objection to the Wallace lamp is, that the light does not remain at one point, but travels along the whole extent of the carbons. It will not be easy to design a glass shade which will be suitable for a light thus changing in position.