Contributions from

the Museum of History and Technology:

Paper 8

The Natural Philosophy of
William Gilbert and His Predecessors

W. James King

By W. James King

THE NATURAL PHILOSOPHY OF

WILLIAM GILBERT

AND HIS PREDECESSORS

The year 1600 saw the publication by an English physician, William Gilbert, of a book on the loadstone. Entitled De magnete,[1] it has traditionally been credited with laying a foundation for the modern science of electricity and magnetism. The following essay is an attempt to examine the basis for such a tradition by determining what Gilbert's original contributions to these sciences were, and to make explicit the sense in which he may be considered as being dependent upon earlier work. In this manner a more accurate estimate of his position in the history of science may be made.

One criterion as to the book's significance in the history of science can be applied almost immediately. A number of historians have pointed to the introduction of numbers and geometry as marking a watershed between the modern and the medieval understanding of nature. Thus A. Koyré considers the Archimedeanization of space as one of the necessary features of the development of modern astronomy and physics.[2] A. N. Whitehead and E. Cassirer have turned to measurement and the quantification of force as marking this transition.[3] However, the obvious absence[4] of such techniques in De magnete makes it difficult to consider Gilbert as a founder of modern electricity and magnetism in this sense.

There is another sense in which it is possible to contend that Gilbert's treatise introduced modern studies in these fields. He has frequently been credited with the introduction of the inductive method based upon stubborn facts, in contrast to the methods and content of medieval Aristotelianism.[5] No science can be based upon faulty observations and certainly much of De magnete was devoted to the destruction of the fantastic tales and occult sympathies of the Romans, the medieval writers, and the Renaissance. However, let us also remember that Gilbert added few novel empirical facts of a fundamental nature to previous observations on the loadstone. Gilbert's experimental work was in large part an expansion of Petrus Peregrinus' De magnete of 1269,[6] and a development of works like Robert Norman's The new attractive,[7] in which the author discussed how one could show experimentally the declination and inclination of a magnetized needle, and like William Borough's Discourse on the variation of the compass or magnetized needle,[8] in which the author suggested the use of magnetic declination and inclination for navigational purposes but felt too little was known about it. That other sea-going nations had been considering using the properties of the magnetic compass to solve their problems of navigation in the same manner can be seen from Simon Stevin's De havenvinding.[9]

Instead of new experimental information, Gilbert's major contribution to natural philosophy was that revealed in the title of his book—a new philosophy of nature, or physiology, as he called it, after the early Greeks. Gilbert's attempt to organize the mass of empirical information and speculation that came from scholars and artisans, from chart and instrument makers, made him "the father of the magnetic Philosophy."[10]

Gilbert's De magnete was not the first attempt to determine the nature of the loadstone and to explain how it could influence other loadstones or iron. It is typical of Greek philosophy that one of the first references we have to the loadstone is not to its properties but to the problem of how to explain these properties. Aristotle[11] preserved the solution of the first of the Ionian physiologists: "Thales too ... seems to suppose that the soul is in a sense the cause of movement, since he says that a stone has a soul because it causes movement to iron." Plato turned to a similar animistic explanation in his dialogue, Ion.[12] Such an animistic solution pervaded many of the later explanations.

That a mechanical