Theory of Heat

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Longmans, 1871 - Science - 312 pages
This classic sets forth the fundamentals of thermodynamics and kinetic theory simply enough to be understood by beginners, yet with enough subtlety to appeal to more advanced readers, too.
 

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Page 298 - Now let us suppose that such a vessel is divided into two portions, A and B, by a division in which there is a small hole, and that a being, who can see the individual molecules, opens and closes this hole, so as to allow only the swifter molecules to pass from A to B, and only the slower ones to pass from B to A. He will thus, without expenditure of work, raise the temperature of B and lower that of A, in contradiction to the second law of thermodynamics.
Page 72 - The specific gravity of a body is the ratio of its density to that of some standard substance.
Page 160 - For compressible flow this becomes: where y is the ratio of the specific heat at constant pressure to that at constant volume...
Page 143 - It is impossible for a self-acting machine, unaided by any external agency, to convey heat from one body to another at a higher temperature ; or heat cannot of itself (that is, without compensation) pass from a colder to a warmer body.
Page 22 - Temperature. — The temperature of a body is its thermal state considered with reference to its power of communicat.ing heat to other bodies.
Page 14 - ... warmed, though the lowest layer is always the hottest. As the temperature increases, the absorbed air which is generally found in ordinary water, is expelled and rises in small bubbles without noise. At last the water in contact with the heated metal becomes so hot that, in spite of the pressure of the atmosphere on the surface of the water, the additional pressure due to the water in the vessel, and the cohesion of the water itself, some of the water at the bottom is transformed into steam,...
Page 298 - But if we conceive a being whose faculties are so sharpened that he can follow every molecule in its course...
Page 268 - Maxwell denned the coefficient of viscosity as follows: "The coefficient of viscosity of a substance is measured by the tangential force on unit area of either of two horizontal planes at unit distance apart, one of which is fixed while the other moves with unit velocity, the space between being filled with the viscous substance.
Page 112 - No separation into liquid and vapour can be detected, but at the same time very small variations of pressure or of temperature produce such great variations of density that flickering movements are observed in the tube ' resembling in an exaggerated form the appearances exhibited during the mixture of liquids of different densities, or when columns of heated air ascend through colder strata.
Page 266 - ... alteration is just going to take place is called the limit of perfect elasticity. If the stress, when it is maintained constant, causes a strain or displacement in the body which increases continually with the time, the substance is said to be viscous.

About the author (1871)

James Maxwell was a British physicist who developed a standard theoretical model for the modern understanding of electricity and magnetism. He showed that these two phenomena are two aspects of the same field and as a result he unified and systematized a vast field of research. Maxwell took many diverse observations and qualitative concepts developed by Michael Faraday and others, formulating them into a unified theory between 1864 and 1873. On the basis of this theory, Maxwell predicted that electromagnetic waves should exist and travel with the speed of light, and he identified light as a form of electromagnetic radiation. Both of these predictions were experimentally confirmed. Maxwell's other great contribution to physics was formulating a mathematical basis for the kinetic theory of gases. Using a statistical approach, he related the velocity of the molecules in a gas to its temperature, showing that heat results from the motion of molecules. Maxwell's result had been conjectured for some time, but it had never been supported experimentally. Maxwell then expanded his research to study viscosity, diffusion, and other properties of gases. Maxwell also provided the first satisfactory explanation of Saturn's rings. He established on theoretical grounds that the rings are not solid but rather composed of many small, fragmented objects that orbit Saturn.

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