[2] Provins, town 57 miles southeast of Paris.
[3] Southey, "Omniana," Vol. I., p. 213, ed. 1812.
[4] Annali di Matematica pura ed applicata. Rome, 1865.
[5] Also in Rees Encyclopedia, article Compass.
[CHAPTER II.]
Norman and Gilbert.
We have seen that in the thirteenth century the directive property of the lodestone was recognized by Peregrinus and used by him in his pivoted compass; and that in the fifteenth, Columbus discovered magnetic declination on sea as well as its variation with place.
The next cardinal fact in terrestrial magnetism, magnetic dip, was discovered in 1576 by Robert Norman, a compass-maker of Limehouse, London. Norman possessed many of the fine qualities of mind, hand and disposition that are indispensable in the make-up of the original investigator. In pivoting his compass-needles, he soon noticed that, however carefully they were balanced before being magnetized, they did not remain horizontal after magnetization, the north-seeking end always going down through a small angle. He next had the happy idea of swinging a needle on a horizontal axis, so that it might be free to move up and down in a vertical plane, with the result that the north-seeking end again went down through a constant but much greater angle.
