a distance of only three inches. A similar experiment had been made by Descartes. I concluded, therefore, said Brugmans, that if the iron plates were interposed between the magnet and the needle lengthways, instead of breadthways or right across, the action of the magnet on the magnetic needle would, in consequence of this great increase of resistance, become still weaker, or perhaps evanescent. But not less to my surprise than my admiration, I found that the power of the magnet was so far from being diminished by this change in the relative position of the iron-plates; that, on the contrary, it now extended to a far greater distance than when no iron at all was interposed. Some time after the same philosopher, out of several iron bars, the sides of which were an inch broad each, composed a single bar of the length of more than ten feet, and observed the magnetism make its way through the whole mass. But, in order to try whether the action could be propagated to any length indefinitely, after several experiments with bars of intermediate lengths, in all of which he had succeeded, he tried a four-cornered iron rod, more than twenty feet long, and it was at this length that the magnetic power first began to be diminished. So far Brugmans.
But the shortest way for any one to convince himself of this relation of the magnetic power would be, in one and the same experiment, to interpose the same piece of iron between the magnet and the compass needle first breadthways; and in this case it will be found that the needle, which had been previously deflected by the magnet from its natural position at one of its poles, will instantly resume the same, either wholly or very nearly so—then to
