(under subclass 230) Subject matter wherein the light standard is of the incandescent type and wherein the incandescence may be varied as by a variable resistance in series with the power supply to the filaments of the incandescent lamp.
(1) Note. In this subclass the lamp is usually adjusted to proper incandescence and the light intensity determined from a scale reading of the variable resistance.
SEE OR SEARCH THIS CLASS, SUBCLASS:
46+, for an optical pyrometer with an electrically variable incandescent standard.
