Abstract
A smoke guide for use with white plumes has been developed by suspending size-graded industrial diamond dust in transparent plastic blocks. The guide consists of a series of four blocks containing dusts with white light transmittances of 20, 40, 60, and 80 per cent and scattering characteristics similar to those of white (oil) plumes commonly used for training smoke inspectors. The luminances of experimental plumes and guides with like transmittances are compared when viewed under different illuminating and viewing conditions. Similar tests with a U. S. Public Health Service Black Smoke Guide are also described.