REFERENCES.--Humboldt, “Cosmos,” 1849, Vol. II. p. 658, and 1859, Vol. V. p. 56; L. A. Bauer, “U. S. Magn. Tables,” 1902, p. 26. Although based upon very imperfect observations, the magnetic charts thus devised by Alonzo de Santa Cruz antedate by more than one hundred and fifty years the work of Dr. Halley (at A.D. 1683). =A.D. 1544.=--Hartmann (Georg) a vicar of the church of Saint Sebaldus, at Nuremberg, writes March 4, to the Duke Albrecht of Prussia, a letter which was brought to light by Moser and which reads as follows: “Besides, I find also this in the magnet, that it not only turns from the north and deflects to the east about nine degrees, more or less, as I have reported, but it points downward. This may be proved as follows: I make a needle a finger long, which stands horizontally on a pointed pivot, so that it nowhere inclines toward the earth, but stands horizontal on both sides; but, as soon as I stroke one of the ends (with the loadstone) it matters not which end it be, then the needle no longer stands horizontal, but points downward (_fällt unter sich_) some nine degrees, more or less. The reason why this happens I was not able to indicate to his Royal Majesty.” The above seems to establish the fact that Hartmann first observed the dip of the magnetic needle independently of Robert Norman. Gilbert refers (“De Magnete,” Book I. chap. i.) to Fortunius Affaitatus--Affaydatus--an Italian physicist who, says he, has some rather silly philosophizing about the attraction of iron and of its turning to the poles, thus alluding to the latter’s small work called “Physicæ (et) ac astronomiæ (astronomicæ) considerationes,” which appeared at Venice in 1549. Nevertheless, it is a question whether Affaitatus was not actually the first to publish the declination of the magnetic needle. (“Biogr. Gén.,” Vol. I. p. 346; Mazzuchelli, “Scrittori d’Italia”; Bertelli, “Mem. sopra P. Peregrino,” p. 115; Adelung, Supplément à Jocher, “Allgem. Gelehrten-Lexicon”; Johann Lamont, “Handbuch des Magnetismus,” Leipzig, 1867, p. 425; J. C. Poggendorff, “Biogr.-Lit. Handwörterbuch,” Leipzig, 1863, Vol. I. p. 15; Michaud, “Biogr. Univ. Anc. et Mod.,” Vol. I. p. 208, Paris, 1843; Brunet, “Manuel,” Paris, 1860; “Biog. Cremonese de Lancetti”; M. le Dr. Hœfer, “Biog. Gen.,” Paris, 1852, Vol. I. p. 346.) REFERENCES.--Dove, “Repertorium der Physik,” Vol. II, 1838, pp. 129–130; Poggendorff, “Geschichte der Physik,” 1879, p. 273; L. Hulsius, “Descriptio et usus,” Nürnberg, 1597; “Ency. Brit.,” 1883, Vol. XV. p. 221; P. Volpicelli, “Intorno alle prime ... magnete” (Atti dell Acad. Pont. de Nuov. Lincei, XIX. pp. 205, 210).