THE LETTER OF PETRUS PEREGRINUS ON THE MAGNET, A.D. 1269 TRANSLATED BY BROTHER ARNOLD, M.Sc. PRINCIPAL OF LA SALLE INSTITUTE, TROY WITH INTRODUCTORY NOTICE BY BROTHER POTAMIAN, D.Sc. PROFESSOR OF PHYSICS IN MANHATTAN COLLEGE, NEW YORK NEW YORK McGRAW PUBLISHING COMPANY MCMIV Copyright, 1904, by McGraw Publishing Company INTRODUCTORY The magnetic lore of classic antiquity was scanty indeed, being limited to the attraction which the lodestone manifests for iron. Lucretius (99-55 B. C.), however, in his poetical dissertation on the magnet, contained in _De Rerum Natura_, Book VI.[1] recognizes magnetic repulsion, magnetic induction, and to some extent the magnetic field with its lines of force, for in verse 1040 he writes: Oft from the magnet, too, the steel recedes, Repelled by turns and re-attracted close. And in verse 1085: Its viewless, potent virtues men surprise; Its strange effects, they view with wond’ring eyes When without aid of hinges, links or springs A pendant chain we hold of steely rings Dropt from the stone—the stone the binding source— Ring cleaves to ring and owns magnetic force: Those held above, the ones below maintain, Circle ’neath circle downward draws in vain Whilst free in air disports the oscillating chain. The poet Claudian (365-408 A. D.) wrote a short idyll on the attractive virtue of the lodestone and its symbolism; St. Augustine (354-430), in his work _De Civitate Dei_, records the fact that a lodestone, held under a silver plate, draws after it a scrap of iron lying on the plate. Abbot Neckam, the Augustinian (1157-1217), distinguishes between the properties of the two ends of the lodestone, and gives in his _De Utensilibus_, what is perhaps the earliest reference to the mariner’s compass that we have. Albertus Magnus, the Dominican (1193-1280), in his treatise, _De Mineralibus_, enumerates different kinds of natural magnets and states some of the properties commonly attributed to them; the minstrel, Guyot de Provins, in a famous satirical poem, written about 1208, refers to the directive quality of the lodestone and its use in navigation, as do also Cardinal de Vitry in his _Historia Orientalis_ (1215-1220); Brunetto Latini, poet, orator and philosopher, in his _Trésor des Sciences_, a veritable library, written in Paris in 1260; Raymond Lully, the Enlightened Doctor, in his treatise, _De Contemplatione_, begun in 1272, and Guido Guinicelli, the poet-priest of Bologna, who died in 1276.