Note 18 — Chapter X · Globes and Globe Makers of the Early Seventeenth Century. The Dutch Scientific Masters and Their Preëminent Leadership

Bauer, L. A. Principal Facts Relating to the Earth’s Magnetism. (In: United States Magnetic Declination Tables and Isogonic Charts for 1902. Washington, 1902.) Printed also as a separate; Wolkenhauer, A. Beiträge zur Geschichte der Kartographie und Nautik des 15 bis 17 Jahrhundert. München, 1904; Hellmann, G. Ueber die Kentniss der magnetischen Deklination vor Christopher Columbus. (In: Meteorologische Zeitschrift. Braunschweig, 1906.) Gilbert, W. De Magnete. London, 1600, and reissued in translation in 1893. This work is one of great significance in its treatment of magnetism and electricity. See especially Bk. IV on Variation, Pedro Medina in his Art de Navigar, Valladolid, 1545, contended that the magnetic needle always points to the true north; Stevenson, E. L. Early Spanish Cartography of the New World. (In: Proceedings of the American Antiquarian Society. Worcester, 1909.) Attention is called in this paper to certain errors in early Spanish maps, probably due to a failure to note properly the declination of the magnetic needle.