A Distribution Photometer of New Design

The field of usefulness of the distribution photometer is explained briefly. A review is made of the more common types of distribution photometers. The requirements which had to be met by the photometer described in this paper are outlined. This is followed by a detailed description of the above instrument, including the methods and features of design which were employed to meet the requirements. The ten foot integrating icosahedron is mentioned and an outline given of the methods employed for transferring lighting units of different type from icosahedron to distribution photometer, and vice versa, with a minimum of time and labor. The electrical supply and control system for the entire room, including the two above instruments, is described.