Michael Faraday, his life and work / by Silvanus P. Thompson.

  • Silvanus P. Thompson
Date:
1901
Catalogue details

Licence: In copyright

Credit: Michael Faraday, his life and work / by Silvanus P. Thompson. Source: Wellcome Collection.

    96/346 page 78
    inoperative* on all other substances. Again, while it had been noticed that in houses which had been struck by lightning knives, needles, and other steel objects near the path of the electric flash had become magnetised, no one had been able, by using the most powerful electric machines, to repeat with certainty the magnetisation of needles. In vain thej- had tried to magnetise knives and wires by sending sparks through them. Sometimes they showed a trace of magnetism, sometimes none. And in the cases where some slight magnetisation resulted, the polarity could not be depended upon. Yan Swinden had written a whole treatise in two volumes on the analogies between electricity and magnetism, but left the real relation between the two more obscure than ever. After the invention, in 1800, of the voltaic pile, which for the first time provided a means of generating a steady flow or current of electricity, several experi- menters, including Oersted himself, had again essayed to discover the long-suspected connection, but with- out success. Oersted was notoriously a poor experi- menter, though a man of great philosophical genius. Having in 1820 a more powerful voltaic battery in operation than previously, he repeated f the operation of bringing near to the compass needle the copper wire that conveyed the current; and, laying it parallel to the needle’s direction, and over or under it, found that the needle tended to turn into a direction at right * Except on nickel and cobalt, which are also para-xuagnetic metals, t For a graphic account by Ilansteen of the circumstances of Oersted’s discovery, see Bence Jones’s “ Life and Letters of Faraday,” vol. ii. p. 390.
    digitised image 1
    digitised image 2
    digitised image 3