[N078003], Technical Note, Thomas Alva Edison, 1879



If you double the radiating surface of the Induction bobbin of a Magneto machine the temperature will be reduced 3/4 That is to say if a given magneto machine has a raditaing surface of two square feet & on a given resistance reaches a constant temperature of 200 then the size of the bobbin be increased to 4 feet surface:-- the temperature will only reach 50 or in other words it will not rise above the atmosphere. The friction of the molecules is the cause of the heat from a wire when a current is passing every wave of energy tends to orient the molecule hence friction & heat Good conductors such as Copper have their molecules oriented easily hence small amount of heat energy evolved by friction & greater current passes & work is not done except at slight extent in orientation, but with crystaline conductor a large amount of work mut be done to orient the molecules & great heat is given out hence these crystaline bodies are poor conductors The crystallic adhsion or force tends to resist orientation. It is probable that the best thermo piles will be those whose molecules resist orientation by electricity the most. The nergy absorbed in any magnetoi machine will be at the square of the diameter of the bobbin, the shaft speed remaining the same.







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[N078003], Technical Note, Thomas Alva Edison, 1879

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Thomas A. Edison Papers, School of Arts and Sciences, Rutgers University