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He spoke with all the fervor of the preacher, with pale face, brilliant eyes, and clenched hands; but in a voice adapted to a drawing room. Phyllis of Philistia could not but admit that, in the phrase of Philistia he had spoken in perfect taste. He had not alluded definitely to the boldness of Ruth or to the calorific course accepted by the aged David.
Experience, finally, rectifying the vague predictions to which the most enlightened minds abandon themselves with so little reserve, shows that the calorific rays which emanate from the plane surface of a heated body have not the same force, the same intensity in all directions; that the maximum corresponds to the perpendicular emission, and the minimum to the emissions parallel to the surface.
I shall not quit this first part of the labours of Fourier without adding, that he has not contented himself with demonstrating with so much felicity the remarkable law which connects the comparative intensities of the calorific rays, emanating under all angles from heated bodies; he has sought, moreover, the physical cause of this law, and he has found it in a circumstance which his predecessors had entirely neglected.
Beneath the tubes that serve to burn the mixture of air and gas, there is placed a metallic gauze, I, the object of which is to prevent the flames from entering the fire place box. These tubes traverse a sheet iron piece, J, which forms the surface of the fire place, and are covered with a layer of asbestos filaments that serve to increase the calorific power of the apparatus. Front View.
We might, then, perhaps explain the different effects of the wear of the carbons serving as rheophores, according as the currents are continuous or alternating, by the different calorific effects produced on these carbons, and by the effects of electric conveyance which are a consequence of the passage of the current through the arc.
But large nuclei, large penumbræ, wrinkles, faculæ, do they indicate an abundant luminous and calorific emission, as Herschel thought; that would be the result of his hypothesis on the existence of very active ascending currents, but direct experience seems to contradict it.
It is natural, however, to suppose that these equivalent apparitions and disappearances correspond to transformations and not to simultaneous creations and destructions. We thus represent energy to ourselves as taking different forms mechanical, electrical, calorific, and chemical capable of changing one into the other, but in such a way that the quantitative value always remains the same.
After giving diagrams and tables to illustrate the geometrical disposition of the areas of fusion, Tresca feels justified in concluding that the development of heat depends upon the form of the faces and the intensity of the shock; that the points of greatest heat correspond to the points of greatest flow of the metal, and that this flow is really the mechanical phenomenon which gives rise to the calorific phenomenon; that for action sufficiently energetic and for bars of sufficient dimensions, about 0.8 of the labor expended on the blow may be found again in the heat; that the figures formed in the melted wax for shocks of less intensity furnish a kind of diagram of the distribution of the heat and of the deformation in the interior of the bar, but that the calculation of the coefficient of efficiency does not yield satisfactory results in the case of moderate blows.
In all these transformations the calorific energy obtained has not, from a practical point of view, the same value at which it started. One cannot, in fact, according to the principle of Carnot, transform it integrally into mechanical energy, since the heat possessed by a body can only yield work on condition that a part of it falls on a body with a lower temperature.
Calorific conductivity is due, in fact, to an exchange of electrons between the hot and the cold regions, the heated electrons having the greater velocity, and consequently the more considerable energy. The calorific exchanges then obey laws similar to those which govern electric exchanges; and calculation even leads to the exact values which the measurements have given.
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