obtain this, experiments must be made in side-lighted rooms with the height of the window sill from the floor, the size of the opening, and the proportion of glass to wall surface. In the same way with top-light, the height of the outer sky-light from the floor, the treatment of the space between outer and inner lights, the height of the inner glass ceiling, and the proportional size of this last must all be carefully studied, not only in already established and successful museums, but in the town and on the exact spot where the new gallery is to be located.
In general it may be said that if side-light is chosen for pictures and sculpture it should enter from a height, while for objects in cases and for prints a low side-light is preferable.
Intermediate between side-light and top-light is the clerestory system such as is used in the great hall of the Decorative Arts wing of the Metropolitan and in the basilica of the Kaiser Friedrich Museum. Here the light entering very high is reflected on the light walls of the upper part of the room until it becomes thoroughly diffused and loses definite direction. A successfully top-lighted room should have much the same characteristic; the wall surface needs to be lighted rather than the centre of the room and the problem is to so arrange the angle of light that in passing through
