Dynamo-electricity: Its Generation, Application, Transmission, Storage and Measurement

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D. Appleton, 1890 - 867 pages
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Page 765 - French weight. The gramme is the weight of a cubic centimetre of distilled water at the temperature of zero.
Page 258 - The same quantity of electricity which, passed in a given time, can heat an inch of platina wire of a certain diameter red hot, can also heat a hundred, a thousand, or any length of the same wire to the same degree, provided the cooling circumstances are the same for every part in all cases.
Page 768 - The quality of the conductor in virtue of which it prevents the performance of more than a certain amount of work in a given time by a given electromotive force is called its electrical resistance. The resistance of a conductor is therefore inversely proportional to the work done in it when a given electromotive force is maintained between its two ends...
Page 763 - ... astronomers, in common with all workers in mathematical dynamics, according to which the unit of force is that force, which, acting on unit of mass for unit of time, generates a velocity equal to unit of velocity.
Page 104 - FIG. 46. the current circulating through m renders it magnetic and attracts the armature, a, thus separating the electrodes, when, on the weakening of the current, the elasticity of the rod, b, again restores the contact. During the movement of the negative electrode, since it is caused to occur many times per second, the positive electrode, though partially free to fall, cannot follow the rapid motions of the negative electrode, and therefore does not rest in permanent contact with it. The...
Page 29 - The advantage of winding the wire in grooves or depressions in the armature is twofold; first, the projecting portions of the armature between the sections of wire may be made to revolve very close to the poles of the magnets from which the magnetic force is derived.
Page 54 - ... by many previous experimenters. The difficulties encountered in the measurement of the light, arising from the difference in colour, were at first thought to be considerable, but further practice and experience enabled the observer to overcome them to such an extent, that the error arising from this cause is inconsiderable, being greatly less than that due to the fluctuations of the electric arc itself.
Page 104 - In order to obtain an excellent but free contact of the arm,/, with the positive electrode, the rod, r, made of iron or other suitable -metal, passes through a cavity filled with mercury, placed in electrical contact with the arm,/. Since the mercury does not wet the metal rod, r, or...
Page 50 - ... magnets, and the current generated depends on the change of polarity of the cores. It will be seen that this constitutes a double machine, each series of coils, with its commutator, being capable of use quite independently of the other; but in practice the electrical connections are so made, that the currents generated in the two series of armature coils pass through the field-magnet coils, and are joined in one external circuit. This form of armature also presents considerable uncovered surface...
Page 70 - It is evident, indeed, that no determinations made with an unknown or abnormal external resistance can be of any value, since the proportion of work done, in the several portions of an electrical circuit, depends upon, and varies with, the resistances they offer to its passage. If, therefore...

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