Meteorological observations and essays / By John Dalton.

  • John Dalton
Date:
1834
Catalogue details

Licence: Public Domain Mark

Credit: Meteorological observations and essays / By John Dalton. Source: Wellcome Collection.

    86/280 (page 60)
    SECTION ELEVENTH. On Magnetism, and the variation of the Needle. In order to understand the additional observations, and the subsequent Essay on the aurora borealis, a competent knowledge of magnetism is requisite ; and as the principal facts relating to that subject are few and simple, we have thought it would not be amiss to state them here, for the sake of such as may not be previously acquainted therewith. The Loadstone, or natural Magnet, is a mineral production, found in the bowels of the earth, amongst rich iron ores, of which it is one itself ; its distinguished property is that of attracting iron and steel. This property, which is called mag- netism, is communicable to steel only, so as to be permanent ; and to zron when within the influence of a magnet, but as soon as the magnet is with- drawn, the magnetism of iron ceases. Every magnet has two opposite points or ex- tremities, called its poles; the one is denominated its north pole, and the other its south pole ; and the attraction of the magnet is strongest at its poles. If an oblong bar of tempered steel (it will answer well if five inches long, half an inch broad, and a quarter of an inch thick) be rubbed over from one end to the other, always the same way, by either pole of the magnet, it will be converted into a