Volume 2

Fragments of science : a series of detached essays, addresses, and reviews / by John Tyndall.

  • John Tyndall
Date:
1879
Catalogue details

Licence: Public Domain Mark

Credit: Fragments of science : a series of detached essays, addresses, and reviews / by John Tyndall. Source: Wellcome Collection.

    453/508 (page 441)
    upon the principle of the magneto-electric machine, employing permanent magnets as the exciters of the induced currents. Using the magnets of the Alliance Company, by a skilful disposition of his bobbins, M. de Meritens produces with eight magnets a light equal to that produced by forty magnets in the Alliance machines. While the space occupied is only one-fifth, the cost is little more than one-fourth of the latter. In the de Meritens machine the commutator is abolished. The internal heat is hardly sensible, and the absorption of power, in relation to the effects produced, is small. With his larger machines M. de Meritens maintains a considerable number of lights in the same circuit.' In relation to this subject, inventors fall into two classes, the contrivers of regulators and the constructors of machines. M. Eapieff has hitherto belonged to in- ventors of the first class, but I have reason to know that he is engaged on a machine which, when complete, will place him in the other class also. Instead of two single carbon rods, M. Eapieff employs two pairs of rods, each pair forming a V. The light is produced at the common junction of the four carbons. The device for regulating the light is of the simplest character. At the bottom of the stand which supports the carbons are two small electro-magnets. One of them, when the current passes, draws the carbons together, and in so doing throws itself out of circuit, leaving the control of the light to the other. The carbons are caused to approach each other by a descending weight, which acts in conjunction with the electro-magnet. Through the liberality of the proprietors of the Times, every facility ' The small machine transforms one-and-a-quarter horse-power into neat and light, yielding about ] ,900 candles; the large machine transforms five-horse power, yielding about 9,000 candles