THE ILLUMINANT. The electric arc is the most suitable ant for cinematograph projection. A resistance, or a choking coil, properly adjusted to the current, will be required. Where electric light is unobtainable, the oxy-hydrogen light may be employed. It should be mentioned that the leading British insurance companies lutely refuse to entertain the use of an ether saturator ; if this is used it must be at the operator's own risk. The Nernst-Paul power Electric Projection Lamp has several advantages ; it may be connected to any ordinary incandescent fitting, or other source of supply, carries its own resistance, and will give a light sufficient for a ten-foot disc in a ball of moderate size.
Cowl]fan; FILM~.
Cinematograph films are sometimes, though not very frequently, tinted or coloured. This is a work requiring much patience and the greatest care, since the outlines of objects have to be very strictly kept to. The necessity for this will be readily understood when it is con sidered that any slight overlapping of colour, or lack of identity in this respect between succeeding pictures, will cause the object to apparently bulge out or contract ; or, in other words, will give rise to an objectionable move ment in what should. perhaps, be stationary.
The number of pictures to be dealt with also renders the operation very tedious. Obviously, only the most transparent colours should be used, applied as lightly as possible. Aniline dyes are very suitable for the purpose. 'Films of special subjects are often improved by toning to a warm, or any other desired colour. Fire scenes, for instance, may be effectively toned to a red, or seascapes to a green tint. Attempts have been made to use triple projection for the production of animated photographs in natural colours, but the inevitable loss of light is, as yet, a difficulty to overcome.