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Coming of Electric Lighting 235 tones of the pioneer carbon incandescent filament lamp in Great Britain, may be set down as a distinct combination of the arc and incandescent principles. There is the vacuum glass-bulb of the latter in which is placed two elements, and in which the light is derived by striking an arc between the two. A small ball of tungsten with its connecting wire is placed between a trapeze-like formation of filament, and in such a manner as to come near the cross piece of the trapeze, which is known as the ionising fila- ment. With this lamp two switches are required, one being a push switch similar to that used with electric bells. This is pressed for two or three seconds to energise the ionising filament. Then this is released and the ordinary switch is moved. Instantly an arc is struck between the ball of tungsten and the fila- ment. Although the latter is caused to glow, the greater volume of light proceeds from the tungsten ball, while, in addition, there is the arc between the two contributing its proportion of luminosity. With this lamp an extreme concentration of light is obtained, and this is especially valuable where any focusing of light is desired. This feature renders the lamp of inestimable value in one wide field—as the illuminant in connection with projecting apparatus such as that for animated pictures. Hitherto the arc lamp has been employed exclusively for this purpose, and despite the many objections thereto, the greatest of which is the risk of igniting the celluloid film, it has not been superseded, merely because no other form of electric lighting was found to be equally suitable. This new lamp, described as the u pointolite, solves this problem completely, because it offers the lumin-