The Natural Philosophy of William Gilbert and His Predecessors Part 1

The Natural Philosophy of William Gilbert and His Predecessors.

by W. James King.

Until several decades ago, the physical sciences were considered to have had their origins in the 17th century--mechanics beginning with men like Galileo Galilei and magnetism with men like the Elizabethan physician and scientist William Gilbert.

Historians of science, however, have traced many of the 17th century's concepts of mechanics back into the Middle Ages.

Here, Gilbert's explanation of the loadstone and its powers is compared with explanations to be found in the Middle Ages and earlier.

From this comparison it appears that Gilbert can best be understood by considering him not so much a herald of the new science as a modifier of the old.

THE AUTHOR: W. James King is curator of electricity, Museum of History and Technology, in the Smithsonian Inst.i.tution's United States National Museum.

The year 1600 saw the publication by an English physician, William Gilbert, of a book on the loadstone. Ent.i.tled _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.

[1] William Gilbert, _De magnete, magneticisque corporibus et de magno magnete tellure; physiologia nova, plurimis & argumentis, & experimentis, demonstrata_, London, 1600, 240 pp., with an introduction by Edward Wright. All references to Gilbert in this article, unless otherwise noted, are to the American translation by P. Fleury Mottelay, 368 pp., published in New York in 1893, and are designated by the letter M. However, the Latin text of the 1600 edition has been quoted wherever I have disagreed with the Mottelay translation.

A good source of information on Gilbert is Dr. Duane H. D.

Roller's doctoral thesis, written under the direction of Dr.

I. B. Cohen of Harvard University. Dr. Roller, at present Curator of the De Golyer Collection at the University of Oklahoma, informed me that an expanded version of his dissertation will shortly appear in book form. Unfortunately his researches were not known to me until after this article was completed.

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. Koyre considers the Archimedeanization of s.p.a.ce as one of the necessary features of the development of modern astronomy and physics.[2] A. N. Whitehead and E. Ca.s.sirer 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.

[2] Alexandre Koyre, _etudes galileennes_, Paris, 1939.

[3] Alfred N. Whitehead, _Science and the modern world_, New York, 1925, ch. 3; Ernst Ca.s.sirer, _Das Erkenntnisproblem_, ed. 3, Berlin, 1922, vol. 1, pp. 314-318, 352-359.

[4] However, see M: pp. 161, 162, 168, 335.

[Ill.u.s.tration: Figure 1.--WILLIAM GILBERT'S BOOK ON THE LOADSTONE, t.i.tLE PAGE OF THE FIRST EDITION, FROM A COPY IN THE LIBRARY OF CONGRESS. (_Photo courtesy of the Library of Congress._)]

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 compa.s.s 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 compa.s.s to solve their problems of navigation in the same manner can be seen from Simon Stevin's _De havenvinding_.[9]

[5] For example, William Whewell, _History of the inductive sciences_, ed. 3, New York, 1858, vol. 2, pp. 192 and 217; Charles Singer, _A short history of science to the nineteenth century_, Oxford, 1943, pp. 188 and 343; and A. R. Hall, _The scientific revolution_, Boston, 1956, p. 185.

[6] _Petri Peregrini maricurtenis, de magnete, seu rota perpetui motus, libellus_, a reprint of the 1558 Angsburg edition in J. G. G. h.e.l.lmann, _Rara magnetica_, Berlin, 1898, not paginated. A number of editions of Peregrinus, work, both ascribed to him and plagiarized from him, appeared in the 16th century (see Heinz Balmer, _Beitrage zur Geschichte der Erkenntnis des Erdmagnetismus_, Aarau, 1956, pp. 249-255).

[7] h.e.l.lmann, _ibid._, Robert Norman, _The newe attractive, containyng a short discourse of the magnes or lodestone, and amongest other his vertues, of a newe discovered secret and subtill propertie, concernyng the declinyng of the needle, touched therewith under the plaine of the horizon. Now first founde out by Robert Norman Hydrographer_. London, 1581. The possibility is present that Norman's work was a direct stimulus to Gilbert, for Wright's introduction to _De magnete_ stated that Gilbert started his study of magnetism the year following the publication of Norman's book.

[8] h.e.l.lman, _ibid._, William Borough, _A discourse of the variation of the compa.s.se, or magneticall needle. Wherein is mathematically shewed, the manner of the observation, effects, and application thereof, made by W. B. And is to be annexed to the newe attractive of R. N._ London, 1596.

[9] h.e.l.lman, _ibid._, Simon Stevin, _De havenvinding_, Leyden, 1599. It is interesting to note that Wright translated Stevin's work into English.

Instead of new experimental information, Gilbert's major contribution to natural philosophy was that revealed in the t.i.tle of his book--a new philosophy of nature, or physiology, as he called it, after the early Greeks. Gilbert's attempt to organize the ma.s.s 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]

[10] As Edward Wright was to call him in his introduction.

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.

[11] Aristotle, _On the soul_, translated by W. S. Hett, Loeb Cla.s.sical Library, London, 1935, 405a20 (see also 411a8: "Some think that the soul pervades the whole universe, whence perhaps came Thales' view that everything is full of G.o.ds").

[12] Plato, _Ion_, translated by W. R. M. Lamb, Loeb Cla.s.sical Library, London, 1925, 533 (see also 536).

That a mechanical explanation is also possible was shown by Plato in his _Timaeus_.[13] He argued that since a vacuum does not exist, there must be a plenum throughout all s.p.a.ce. Motion of this plenum can carry objects along with it, and one could in this manner explain attractions like that due to amber and the loadstone.

[13] Plato, _Timaeus_, translated by R. G. Bury, Loeb Cla.s.sical Library, London, 1929, 80. It is difficult to determine which explanation Plato preferred, for in both cases the speaker may be only a foil for Plato's opinion rather than an expression of these opinions.

Another mechanical explanation was based upon a postulated tendency of atoms to move into a vacuum rather than upon the latter's non-existence. Lucretius restated this Epicurean explanation in his _De rerum natura_.[14] Atoms from the loadstone push away the air and tend to cause a vacuum to form outside the loadstone. The structure of iron is such that it, unlike other materials, can be pushed into this empty s.p.a.ce by the thronging atoms of air beyond it.

[14] Lucretius, _De rerum natura_, translated by W. H. D.

Rouse, Loeb Cla.s.sical Library, London, 1924, bk. VI, lines 998-1041.

Galen[15] returned to a quasi-animistic solution in his denial of Epicurus' argument, which he stated somewhat differently from Lucretius. One can infer that Galen held that all things have, to a greater or lesser degree, a sympathetic faculty of attracting its specific, or proper, quality to itself.[16] The loadstone is only an inanimate example of what one finds in nutritive organs in organic beings.

[15] Galen, _On the natural faculties_, translated by A. S.

Brock, Loeb Cla.s.sical Library, London, 1916, bk. 1 and bk. 3.

A view similar to this appeared in Plato, _Timaeus_, 81 (see footnote 13).

[16] This same concept was to reappear in the Middle Ages as the _inclinatio ad simile_.

One of the few writers whose explanations of the loadstone Gilbert mentioned with approval is St. Thomas Aquinas. Although the medieval scholastic philosophy of St. Thomas seems foreign to our way of thinking, it formed a background to many of Gilbert's concepts, as well as to those of his predecessors, and it will a.s.sist our discussion to consider briefly Thomist philosophy and to make its terminology explicit at this point.[17]

[17] The background for much of the following was derived from Annaliese Maier, _An der Grenze von Scholastik und Naturwissenchaft_, ed 2, Rome, 1952.

In scholastic philosophy, all beings and substances are a coalescence of inchoate matter and enacting form. Form is that which gives being to matter and which is responsible for the "virtus" or power to cause change, since matter in itself is inert. Moreover, forms can be grasped intellectually, whence the nature of a being or a substance can be known. Any explanation of phenomena has to be based upon these innate natures, for only if the nature of a substance is known can its properties be understood. Inanimate natures are determined by observation, abstraction, and induction, or by cla.s.sification.[18]

[18] St. Thomas' epistemology for the natural inanimate world was based upon Aristotle's dictum: that which is in the mind was in the senses first.

The nature of a substance is causally prior to its properties; while the definition of the nature is logically prior to these properties.

Thus, what we call the theory of a substance is expressed in its definition, and its properties can be deduced from this definition.

The world of St. Thomas is not a static one, but one of the Aristotelian motions of quant.i.ty (change of size), of quality (alteration), and of place (locomotion). Another kind of change is that of substance, called generation and corruption, but this is a mutation, occurring instantly, rather than a motion, that requires time. In mutation the essential nature is replaced by a new substantial form.

All these changes are motivated by a causal hierarchy that extends from the First Cause, the "Dator Formarum," or Creator, to separate intellectual substances that may be angels or demons, to the celestial bodies that are the "generantia" of the substantial forms of the elements and finally to the four prime qualities (dry and wet, hot and cold) of the substantial forms. Accidental forms are motivated by the substantial forms through the instrumentality of the four prime qualities, which can only act by material contact.

The only causal agents in this hierarchy that are learned through the senses are the tangible qualities. Usually the prime qualities are not observed directly, but only other qualities compounded of them. One of the problems of scholastic philosophy was the incorporation, into this system of efficient agents, of other qualities, such as the qualities of gravity and levity that are responsible for upward and downward motion.

Besides the causal hierarchy of forms, the natural world of St. Thomas existed in a substantial and spatial hierarchy. All substances whether an element or a mixture of elements have a place in this hierarchy by virtue of their nature. If the material were removed from its proper place, it would tend to return. In this manner is obtained the natural downward motion of earth and the natural upward motion of fire.

Local motion can also be caused by the "virtus coeli" generating a new form, or through the qualitative change of alteration. Since each element and mixture has its own natural place in the hierarchy of material substances, and this place is determined by its nature, changes of nature due to a change of the form can produce local motion. If before change the substance is in its natural place, it need not be afterwards, and if not, would then tend to move to its new natural place.

It will be noted that the scholastic explanation of inanimate motion involved the action and pa.s.sion of an active external mover and a pa.s.sive capacity to be moved. Whence the definition of motion that Descartes[19] was later to deride, "motus est actus entis in potentia prout quod in potentia."

[19] Rene Descartes, _Oeuvres_, Charles Adam and Paul Tannery, Paris, 1897-1910, vol. 2, p. 597 (letter to Mersenne, 16 Oct., 1639), and vol. 11 (Le Monde), p. 39. The original definition can be found in Aristotle, _Physics_, translated by P. H. Wickstead and F. M. Cornford, Loeb Cla.s.sical Library, London, 1934, 201a10. Aquinas rephrases the definition as "_Motus est actus existentis in potentia secundum quod huius modi._" See St. Thomas Aquinas, _Opera omnia_, Antwerp, 1612, vol. 2, _Physicorum Aristotelis expositio_, lib. 3, lect. 2, cap. a, p. 29.