WILLIAM GILBERT, AND TERRESTRIAL
MAGNETISM IN THE TIME OF
QUEEN ELIZABETH: A DISCOURSE
BY SILVANUS P. THOMPSON, F.R.S.
WILLIAM GILBERT ANDTERRESTRIAL MAGNETISMIN THE TIME OFQUEEN ELIZABETH.
William Gilbert, thefather of electrical science,was born in Colchester in1540. Educated at St. John'sCollege, Cambridge, wherehe took his degree as Doctorof Medicine in 1569, he settled, after four years offoreign travel, in London in 1573, and was admittedto the Royal College of Physicians, of whichhe became Censor, Treasurer, and, in 1599, President.He was in February, 1601, appointed personalPhysician to the Queen, whom he attended2in her last illness. He came of a well-known EastAnglian family, and held extensive landed estatesin Essex and Suffolk. He survived the Queen onlyeight months, dying November 30th, 1603.
Gilbert's monumental work, theDe Magnete, published in 1600,marks an era in magnetic science.For some four hundred years theemployment of the magnetic needlein navigation had been knownboth in Northern and Southern Europe. While itis possible that the primitive use of the loadstonemay be ascribed to the Baltic, it is certain that theemployment of a pivotted needle, and the additionof a rose of the winds as a compass card both originatedin the Mediterranean. The pivotted needleis described in the Epistle of Peter Peregrinus, writtenin 1269; while the earliest known compass-cardmarked with the initials of the names of the windsis that ascribed to Jachobus Giraldis, of 1426, in theBiblioteca Marciana in Venice. The manner ofuse in Elizabethan times of the loadstone and of thecompass may be gathered from Olaus Magnus(Historia de Gentibus Septentrionalibus, 1555), fromPedro de Medina (Arte de Nauegar, 1545), Martinus3Cortes (Breve compendio de la sphera, 1556),Blundevile (Exercises, 1594), Norman (Newe Attractive,1581), Borough (A discours of the Variationof the Cumpas, 1581), Pedro Nuñez (InstrumentaArtis Navigandi, 1592), Barlow (The NavigatorsSupply, 1597), Nautonier (Mécometrie de l'Eyman,1602), and Stevin (Die Havenvinding, 1599).
At the time when steering by the compass wasintroduced into navigation, the compass pointedin Middle Europe so nearly truly to the north thatwith the rough instrumental appliances at hand itsdeviation from the true north was seldom noticed,or if noticed ascribed to some error in the settingof the needle. Later the compass-makers began toset their needles slightly askew beneath the card,according to the variation in the place of origin.Norman (1581) states that those used in the Levant,made in Sicily, Genoa, or Venice, had the needlesstraight, while those used in Denmark and Flandershad them set at three-quarters of a point, or awhole point, to the eastward; while those madein Spain, Portugal, France, and England, had theneedles set half a point to the east. Those for Russiawere set at "three seconds of a point." Gilber