LVII.The selectivity of photometric integrators, with particular reference to the photometry of gaseous discharge-tubes

Abstract

Abstract The, paper gives a theoretical treatment of the effect of selectivity of photometric integrators in producing errors in the determinations of the luminous outputs of incandescent lamps and gaseous discharge lamps. The dependence of the error on the method used is investigated. It is shown that in suitable easily realized circumstances measurements of the luminous outputs of neon, sodium, high-pressure and low-pressure mercury lamps should not be in error by more than 1 per cent. due to the selectivity of the photometric integrator.