The Electric Light in Its Practical Application

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E. & F. N. Spon, 1879 - Electric lighting - 240 pages
 

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Page 27 - 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...
Page 139 - Brush machines, if the measurement of the smaller of these machines be taken at the higher speed. The amount of light produced, however, is not the same in these two instances, being considerably greater in the case of the larger machine. The explanation of this apparent anomaly is undoubtedly to be found in the different resistances of the arcs in the two cases. In the large Brush machine the carbons are nearer together than when the small machine is used. This suggests the very plausible explanation,...
Page 26 - A flexible bar, b, of metal is firmly attached at one of its ends to a pillar, p, and bears at its other end an iron armature, a, placed opposite the adjustable pole-piece of the electro-magnet, m. A metal collar, c, supports the negative electrode, the positive electrode being supported by an arm,/., attached to the pillar...
Page 28 - E, at such a distance that when the carbons are consumed as much as is deemed desirable, it comes into contact with a tripping lever, t, which then allows two conducting plugs, attached to the bar v, to fall into their respective mercury cups, attached, respectively, to the positive and negative binding posts by a direct wire. This action practically cuts the lamp out of the circuit.
Page 132 - ... the assumed normal value of the electro-motive force of a Daniell's cell, and R the resistances in the circuit with the battery, gives at once the current In comparison with the total resistances of the circuit, the internal resistance of the battery was so small as to be neglected. The results obtained were as follows : The veber currents, as calculated from the above data, are given in Table VI.
Page 182 - ... or other units of current, it is only necessary, if the variations are not excessive, to average the ordinates, and to determine their value by equation (1), or from a table prepared for that purpose. The error committed in taking the average ordinate instead of the absolute ordinates...
Page 155 - The local action, of dynamo-electric machines is analogous to the local action of a battery, and is equally injurious in its effects upon the- available current. Again, in regard to the internal work of a machine, since all this is eventually reduced to heat in the machine, the temperature during running must continually rise until the loss by radiation and convection into the surrounding air, are eventually equal the production, and the machine will at last acquire a constant temperature.
Page 52 - My first impression of this peculiar action of the arc was, that it was due to the ascending current of hot air by which it was surrounded. This however was found not to be the cause, as the arc travelled towards the points in whatever position the carbons were placed, whether horizontally or vertically in an inverted position. Moreover, when a pair of carbons were held in the middle by the holders, the arc travelled upwards or downwards to the points, according as the circuit was established above...
Page 36 - ... separate the two carbons and produce the electric light. As the carbons burn away, thus increasing the length of the voltaic arc, the electric current diminishes in strength, owing to the increased resistance. This weakens the magnetism of the helix, and accordingly the core, rod and upper carbon move downward by the force of gravity until the consequent shortening of the voltaic arc increases the strength of the current and stops such downward movement. After a time, however, the ring will reach...
Page 144 - ... 41 per cent, after deducting friction and the resistance of the air. In this machine the loss of power in friction and local action is the least, the speed being comparative ly low.

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