The Pressure of Radiation on a Clear Glass Vane

Abstract

IN an article on “The Elimination of Gas Action in Experiments on Light Pressure,” read before the American Physical Society in December, 1904, and published in the Physical Review, May, the writer made the following statement:—“A thin vane of clear glass, accurately vertical and mounted radially, may be used to advantage to demonstrate light pressure. If the light has been filtered through several thicknesses of glass there will be but little absorption by the thin vane and its two surfaces will be warmed nearly equally. Consequently the radio-metric effect will be small. The reflection of the radiation at the two surfaces will make a difference of about 16 per cent. between the energy in front of and behind the vane. Hence the light pressure will be about one-sixth of that due to the same light beam falling upon a black surface. The throws for such a vane had only about a ten per cent. variation in a range of air pressures from about 10 mm. to 200 mm. of mercury.”