MAGNETISM.

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238. THE knowledge which the antient naturalists possessed of this subject was extremely imperfect, and affords the strongest proof of their ignorance of the true method of philosophising; for there can hardly be named any object of physical research that is more curious in itself, or more likely to engage attention, than the apparent life and activity of a piece of rude unorganised matter. This had attracted notice in very early times; for Thales attributed the charac teristic phenomenon, the attraction of a piece of iron, to the agency of a mind or soul residing in the magnet. Philosophers seem to have been contented with this lazy notice of a slight suggestion, unbecoming an inquirer, and rather such as might be expected from the most incurious peasant. Even Aristotle has collected no information that is of any importance. We know that the general imperfection of ancient physics has been ascribed to the little importance that was attached to the knowledge of the material world by the

philosophers of Greece and Rome, who thought human nature, the active pursuits of men, and the science of public affairs, the only objects deserving their attention. Most of the great philosophers of antiquity were also great actors on the stage of human life, and despised acquisitions which did not tend to accomplish them for this dignified employment: but they have not given this reason themselves, though none was more likely to be uppermost in their mind. Socrates dissuades from the study of material nature, not because it was unworthy of the attention of his pupils, but because it was too difficult, and that certainty was not attainable in it. Nothing can more distinctly prove their ignorance of what is really attainable in science, namely, the knowledge of the laws of nature, and their ignorance of the only method of acquiring this knowledge, viz. observation and experiment. They had entertained the hopes of discovering the causes of things, and had formed their philosophical language, and their mode of research, in conformity with this hopeless project. Making little advances in the discovery of the causes of the phenomena of material nature, they deserted this study for the study of the conduct of man; not because the discovery of causes was more easy and frequent here, but because the study itself was more immediately interesting, and because any thing like superior knowledge in it puts the possessor in the desirable situation of an adviser, a man of superior wisdom; and as this study was closely connected with morals, the character of the philosopher acquired an eminence and dignity which was highly flattering to human vanity. Their procedure in the moral and intellectual sciences is strongly marked with the same ignorance of the true method of philosophising; for we rarely find them forming general propositions on copious inductions of facts in the conduct of men. They always proceed in the syn thetic method, as if they were fully conversant in the first principles of human nature, and had nothing to do but to make the application, according to the established forms of

logic. While we admire, therefore, the sagacity, the penetration, the candid observation, and the happy illustration, to be found in the works of the ancient moralists and writers on jurisprudence and politics, we cannot but lament that such great men, frequently engaged in public affairs, and therefore having the finest opportunities for deducing general laws, have done so little in this way; and that their writings, however engaging and precious, cannot be considered as any thing more refined than the observations of judicious and worthy men, with all the diffuseness and repetition of ordinary conversation. All this has arisen from the want of a just notion of what is attainable in this department of science, namely, the laws of intellectual and moral nature; and of the only possible method of attaining this knowledge, viz. observation and experiment, and the formation of general laws by the induction of particular facts.

239. We have been led into these reflections by the inattention of the ancients to the curious phenomena of magnetism; which must have occurred in considerable and entertaining variety to any person who had taken to the experimental method. And we have hazarded these free remarks, expecting the acquiescence of our readers, because the superior knowledge which we, in these later days, have acquired of the magnetical phenomena, were the first fruits of the true method of philosophising. This was pointed out to the learned world in 1590 by our celebrated countryman Chancellor Bacon, in his two great works, the Novum Organum Scientiarum, and De Argumentis Scientiarum. Dr. Gilbert of Colchester, a philosopher of eminence in many respects, but chiefly because he had the same just views of philosophy with his noble countryman, published about the same time his Physiologia Nova, seu Tractatus de Magnete et Corporibus magneticis. In the introduction, he recounts all the knowledge of the antients on the subject, and their supine inattention to what was so entirely in their hands; and the impossibility of ever adding to the stock of useful knowledge,

so long as men imagined themselves to be philosophising while they were only repeating a few cant words, and the unmeaning phrases of the Aristotelian school. It is curious to remark the almost perfect sameness of Dr. Gilbert's sentiments and language with those of Lord Bacon. They both charge, in a peremptory manner, all those who pretend to inform others, to give over their dialectic labours, which are nothing but ringing changes on a few trite truths, and many unfounded conjectures, and immediately to betake themselves to experiment. He has pursued this method on the subject of magnetism with wonderful ardour, and with equal genius and success; for Dr. Gilbert was possessed both of great ingenuity, and a mind fitted for general views of things. The work contains a prodigious number and variety of observations and experiments, collected with sagacity from the writings of others, and instituted by himself with considerable expence and labour. It would indeed be a miracle if all Dr. Gilbert s general inferences were just, or all his experiments accurate. It was untrodden ground. But, on the whole, this performance contains more real information than any writing of the age in which he lived, and is scarcely exceeded by any that has appeared since. We may hold it with justice as the first fruits of the Baconian or experimental philo sophy.

This work of Dr. Gilbert's relates chiefly to the loadstone, and what we call magnets, that is, pieces of steel which have acquired properties similar to those of the loadstone. But he extends the term magnetism, and the epithet magnetic, to all bodies which are affected by loadstones and magnets in a manner similar to that in which they affect each other. In the course of his investigation, indeed, he finds that these bodies are only such as contain iron in some state or other: and in proving this limitation, he mentions a great variety of phenomena which have a considerable resemblance to those which he allows to be magnetical, namely, those which he called electrical, because they were produced in the same

way that amber is made to attract and repel light bodies. He marks with care the distinctions between these and the characteristic phenomena of magnets. He seems to have known, that all bodies may be rendered electrical, while ferrugineous substances alone can be made magnetical.

240. It is not saying too much of this work of Dr. Gilbert's to affirm, that it contains almost every thing that we know about magnetism. His unwearied diligence in searching every writing on the subject, and in getting information from navigators, and his incessant occupation in experiments, have left very few facts unknown to him. We meet with many things in the writings of posterior inquirers, some of them of high reputation, and of the present day, which are published and received as notable discoveries, but are contained in the rich collection of Dr. Gilbert. Dr. Gilbert's book, although one of those which does the highest honour to our country, is less known in Britain than on the Continent. Indeed we know but of two British editions of it, which are both in Latin; and we have seen five editions published in Germany and Holland before 1628. We earnestly recommend it to the perusal of the curious reader. He will find more facts in it than in the two large folios of Scarella.

241. In mechanical philosophy, a phenomenon is not to be considered as explained, unless we can shew that it is the certain result of the laws of motion applied to matter. It is in this way that the general propositions in physical astronomy, in the theory of machines, in hydraulics, &c. are demonstrated. But the phenomena called magnetical have not as yet obtained such an explanation. We do not see their immediate cause, nor can we say with confidence that they are the effects of any particular kind of matter, acting on the bodies either by impulsion or pressure.

All that can be done here is to class the phenomena in the most distinct manner, according to their generality. In this we obtain a two-fold advantage. We may take it for granted that the most general phenomenon is the nearest allied to

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