The investigations both of Balfour Stewart and of Kirchhoff are based on the idea of an enclosure at uniform temperature and the general results of the reasoning centre in the conclusion that the introduction of any body at the same temperature as the enclosure can make no difference to the streams of radiant energy which we imagine to traverse the enclosure.
James Ward, in Naturalism and Agnosticism (1899), starts from the same phenomenalistic views of Mach and Kirchhoff about mechanics; he proceeds to the hypothesis of duality within experience, which we have traced in James Ward.
The first of these representations is evidently natural, considering the twenty eventful years that have passed; but the second, Kirchhoff holds, is the Ulysses of Calypso's 1 On this point see a paper by Professor Packard in the Trans.
It is important to understand that Mach had developed this economical view of thought in 1872, more than ten years before the appearance of his work on the history of mechanics as he tells us in the preface, where he adds that at a later date similar views were expressed by Kirchhoff in his V orlesungen fiber mathematische Physik (1874).
In a word, Mach and Kirchhoff agree that force is not a cause, convert Newtonian reciprocal action into mere interdependency, and, in old terminology, reduce mechanics from a natural philosophy of causes to a natural history of mere facts.
Mach had begun to put them forward in 1872, and Kirchhoff in 1874.
Inquiries conducted with the refinement which characterizes those of Kirchhoff are always instructive, and his book contains very many just observations; but it is impossible to admit his main conclusions.
According to von Helmholtz and Kirchhoff the velocity in a tube should be less than that in free air by a quantity depending on the diameter of the tube, the frequency of the note used, and the viscosity of the gas (Rayleigh, Sound, vol.
The first edition, with a full commentary based on scientific principles, was that of Aufrecht and Kirchhoff in 1849-1851, and on this all subsequent interpretations are based (Breal, Paris, 1875; Bucheler, Umbrica, Bonn, 1883, a reprint and enlargement of articles in Fleckeisen's Jahrbuch, 18 75, pp. 127 and 313).