An Integrating Photoelectric Meter

Integrating meters for measuring ultraviolet energy have been developed which are unaffected by weather conditions and have been operated in the field without skilled attention for over two years. They have also proved useful in the laboratory, providing radiation dosage measurement within one or two percent. These employ special photo-tubes with a condenser and cold cathode ``trigger'' tube sealed in an extension of the glass envelope, thereby eliminating moisture as a source of leakage. A suitable registering circuit for counting the pulses from the ``trigger'' tube is described. Characteristics are given of typical photo-cells useful in erythemal and bactericidal measurements.