Balfour Stewart's Advances in Radiation Theory

Abstract

THE extremely interesting notes by Sir Arthur Schuster in a recent number of NATURE (January 17, p. 87) may possibly leave with the ordinary reader an impression that Balfour Stewart's contributions to the establishment of the laws of natural radiation were slighter than was actually the case. The considered opinion of the late Lord Rayleigh, set out in Phil. Mag., i. 1901, pp. 98–100, or “Scientific Papers”, iv. pp. 404–5, can hardly be gainsaid. In Stewart's discussion of radiation in an isolated enclosure containing moving bodies, his expressed conviction, that the second law of thermodynamics is only satisfied through the action of mechanical forces necessary to maintain the motion, is only turning round the other way the considerations employed by Boltzmann and by Wien long after, who by means of these mechanical forces (namely, the reaction of radiation pressure) combined with the second law of thermodynamics, deduced the law of structure of natural radiation. Reference may also be made to footnotes appended to the reprint of Stokes's cognate papers in “Math. and Phys. Papers,” iv. especially p. 136.