Whether the pointing is under glass or not, it will probably be advisable to let it face the window. All reflections must be got rid of; sometimes slightly tilting the picture and swinging the back of the camera to compensate for it will be effectual. If possible, the centre of the lens should be opposite the centre of the painting. If the illumination in the camera is weak, focus upon finely grained glass, made by thickly coating a sheet of glass with negative varnish, and then rubbing down the surface with a little finely powdered resin on the ball of the finger: or the ordinary ground glass screen may be oiled. A firmly fixed copying camera, in which focussing is done by moving the back part, would be preferable to an ordinary camera. The lens should be one giving a Hat field and the best possible definition. The stand must be rigid, and, as the exposure is prolonged, every precaution must be taken against vibra-t'on. The plates used must be colour-sensitive; Edwards' instantaneousisochromatic are very suitable. If the picture contains any blues or greens, a yellow screen must be used - a home-made substitute for which can be made by staining to a lemon yellow a fixed unexposed plate in a weak solution of picric acid.

If the stain is too deep, the blues and greens will be rendered too dark. Pyro soda is a most satisfactory developer for i be above-named plates. Use equal parts of each of the following solutions: - No. 1. Pyro, 25gr.; sodium sulphite, 1/2 oz.; water, 5oz. No. 2. Washing soda, 165gr.; water, 5oz. Add one dropper oz.of 10 per cent, potassium bromide solution. The negative should be thin and full of detail, with clear shadows.