Abstract
A method for measuring flame temperatures is described which requires the determination of the intensity and emissivity of the flame at wavelengths within the intensity contour of a resonance spectral line such as a D line of sodium. An experiment is cited to illustrate the method in which a Fabry-Perot interferometer was used as the spectroscopic dispersion instrument. The emissivities were determined by comparing the brightnesses of the mirrored and unmirrored flame. The theory, procedure, and an example of using the method to find the temperature of a submerged zone of a flame are given.