NOTES ON THE DE MAGNETE OF
DR. WILLIAM GILBERT.
During the work of revising and editing the English translation of De Magnete, many points came up for discussion, requiring critical consideration, and the examination of the writings of contemporary or earlier authorities. Discrepancies between the texts of the three known editions—the London folio of 1600, and the two Stettin quartos of 1628 and 1633 respectively—demanded investigation. Passages relating to astrology, to pharmacy, to alchemy, to geography, and to navigation, required to be referred to persons acquainted with the early literature of those branches. Phrases of non-classical Latin, presenting some obscurity, needed explanation by scholars of mediæval writings. Descriptions of magnetical experiments needed to be interpreted by persons whose knowledge of magnetism enabled them to infer the correct meaning to be assigned to the words in the text. In this wise a large amount of miscellaneous criticism has been brought to bear, and forms the basis for the following notes. To make them available to all students of Gilbert, the references are given to page and line both of the Latin folio of 1600 and of the English edition of 1900. S. P. T.
[1] THE GLOSSARY:
Gilbert's glossary is practically an apology for the introduction into the Latin language of certain new words, such as the nouns terrella, versorium, and verticitas, and the adjectival noun magneticum, which either did not exist in classical Latin or had not the technical meaning which he now assigns to them. His terrella, or μικρόγη, as he explains in detail on p. 13, is a little magnetic model of the earth, but in the glossary he simply defines it as magnes globosus. Neither terrella nor versorium appears in any Latin dictionary. No older writer had used either word, though Peter Peregrinus (De Magnete, Augsburg, 1558) had described experiments with globular loadstones, and pivotted magnetic needles suitable for use in a compass had been known for nearly three centuries. Yet the pivotted needle was not denominated versorium. Blondo (De Ventis, Venice, 1546) does not use the term. Norman (The Newe Attractiue, London, 1581) speaks of the "needle or compasse," and of the "wyre." Barlowe (The Navigators Supply, London, 1597) speaks of
the "flie," or the "wier." The term versorium (literally, the turn-about) is Gilbert's own invention. It was at once adopted into the science, and appears in the treatises of Cabeus, Philosophia Magnetica (Ferrara, 1629), and of Kircher, Magnes sive de Arte Magnetica (Coloniæ, 1643), and other writers of the seventeenth century. Curiously enough, its adoption to denote the pivotted magnetic needle led to the growth of an erroneous suggestion that the mariners' compass was known to the ancients because of the occurrence in the writings of Plautus of the term versoriam, or vorsoriam. This appears twice as the accusative case of a feminine noun versoria, or vorsoria, which was used to denote part of the gear of a ship used in tacking-about. Forcellini defines versoria as "funiculus quo extremus veli angulus religatur"; while versoriam capere is equivalent to "reverti," or (metaphorically) "sententiam mutare." The two passages in Plautus are:
Eut. Si huc item properes, ut istuc properas, facias rectius,
Huc secundus ventus nunc est; cape modo vorsoriam;
Hic Favonius serenu'st, istic Auster imbricus:
Hic facit tranquillitatem, iste omnes fluctus conciet.
(in Mercat. Act. V., sc. 2.)