William Gilbert: Deviation
Long loadstone with versoria. Versoria deviate according to the distance from the middle or equator of the loadstone (CD). The deviations are greater the greater the distance of the versoria is from the equator. [ZB Magnet 2] William Gilbert, De Magnete (London: Petrus Short, 1600), Zentralbibliothek Zürich, Alte Drucke und Rara, XVI.28, p. 164.