HISTORY OF MAGNETISM.
Effice, ut interea fera munera militiaï
Per maria ac terras omneis sopita quiescant.
Nam tu sola potes tranquilla pace juvare
Mortales; quoniam belli fera munera Mavors
Armipotens regit, in gremium qui sæpe tuum se
Rejicit, æterno devictus vulnere amoris;
Atque ita suspiciens tereti cervice reposta,
Pascit amore avidos inhians in te, Dea, visus,
Eque tuo pendet resupini spiritus ore.
Hunc tu, Diva, tuo recubantem corpore sancto
Circumfusa super, suaves ex ore loquelas
Funde, petens placidam Romanis, incluta, pacem.
Lucret. i. 31.
O charming Goddess, whose mysterious sway
The unseen hosts of earth and sky obey;
To whom, though cold and hard to all besides,
The Iron God by strong affection glides.
Flings himself eager to thy close embrace,
And bends his head to gaze upon thy face;
Do thou, what time thy fondling arms are thrown
Around his form, and he is all thy own,
Do thou, thy Rome to save, thy power to prove,
Beg him to grant a boon for thy dear love;
Beg him no more in battle-fields to deal.
Or crush the nations with his mailed heel.
But, touched and softened by a worthy flame,
Quit sword and spear, and seek a better fame.
Bid him to make all war and slaughter cease,
And ply his genuine task in arts of peace;
And by thee guided o’er the trackless surge,
Bear wealth and joy to ocean’s farthest verge.
CHAPTER I.
Discovery of Laws of Magnetic Phenomena.
THE history of Magnetism is in a great degree similar to that of Electricity, and many of the same persons were employed in the two trains of research. The general fact, that the magnet attracts iron, was nearly all that was known to the ancients, and is frequently mentioned and referred to; for instance, by Pliny, who wonders and declaims concerning it, in his usual exaggerated style.[1] The writers of the Stationary Period, in this subject as in others, employed themselves in collecting and adorning a number of extravagant tales, which the slightest reference to experiment would have disproved; as, for example, that a magnet, when it has lost its virtue, has it restored by goat’s blood. Gilbert, whose work De Magnete we have [already] mentioned, speaks with becoming indignation and pity of this bookish folly, and repeatedly asserts the paramount value of experiments. He himself, no doubt, acted up to his own precepts; for his work contains all the fundamental facts of the science, so fully examined indeed, that even at this day we have little to add to them. Thus, in his first Book, the subjects of the third, fourth, and fifth Chapters are,—that the magnet has poles,—that we may call these poles the north and the south pole,—that in two magnets the north pole of each attracts the south pole and repels the north pole of the other. This is, indeed, the cardinal fact on which our generalizations rest; and the reader will perceive at once its resemblance to the leading phenomena of statical electricity.
[1] Hist. Nat. lib. xxxvi. c. 25.
But the doctrines of magnetism, like those of heat, have an additional claim on our notice from the manner in which they are exemplified in the globe of the earth. The subject of terrestrial magnetism forms a very important addition to the general facts of magnetic attraction and repulsion. The property of the magnet by which it directs its poles exactly or nearly north and south, when once discovered, was of immense importance to the mariner. It does not [218] appear easy to trace with certainty the period of this discovery. Passing over certain legends of the Chinese, as at any rate not bearing upon the progress of European science,[2] the earliest notice of this property appears to be contained in the Poem of Guyot de Provence, who describes the needle as being magnetized, and then placed in or on a straw, (floating on water, as I presume:)