It is now generally understood that magnetic cars, "based on the same principle as the compass," were used in China much earlier than this. The Helleno-Roman world of antiquity, in describing the magnet, only dwelt on its attraction for iron, and did not notice its power of indicating the poles; whereas the Celestials were aware in the first place of the communication of magnetic fluid to iron, and in the second place of the mysterious power of iron so magnetized, as early as about a.d. 120. The earliest use of the water-compass in China is fixed by Klaproth at a.d. 1111-17; and as to the magnetic figures or magnetic cars with which in earlier times Chinese junks sailed to the south of Asia, and Chinese travellers made their way across the plains and mountains to the west of their country, it must not be assumed that their use was universal. Thus, in the fifth century a.d., when Wu-Ti, afterwards Emperor, stormed Singanfu (417 a.d.), he seized upon one of these as a great curiosity.
It is uncertain, as already remarked, when the complete compass, or even the polarity of the magnet, was first discovered in Europe. We may, however, note the following evidence:
(1) Alexander Neckam, an English monk of St. Albans (born 1157, died 1217), who had studied for some time in the University of Paris, refers more than once to what we may suppose was a compass needle, placed on a metal point.[[286]] This, he implies, was then in common use among sailors, and was not merely a secret of the learned. For, "when the mariners cannot see the sun clearly in murky weather or at night, and cannot tell which way their prow is tending, they put a needle above a magnet, which revolves until its point looks North and then stands still." These words were probably written between 1190-1200.
(2) Guyot de Provins, a satirist of Languedoc, in his poem, La Bible, written about 1200, wishes the Pope would more nearly resemble the Pole-star,[[287]] which always stands immovable in the firmament and guides the sailor. Even in darkness and mist can the Pole-star make itself felt. For the mariner has only to place in a vessel of water a straw pierced by a needle which has been rubbed with a black and ugly stone, that will draw iron to itself; and the point of the needle unfailingly turns towards the Pole-star.
(3) Jacques de Vitry, the French historian-bishop, writing about 1218, in his Historia Orientalis, speaks of "the iron needle which always turns to the North Star after it has touched the magnet" or "adamant."[[288]]
(4) "An unknown singer of the same period" speaks of sailors to Friesland, Venice, Greece or Acre, finding in the Pole-star a sign-post in heaven. Even in darkness and mist the star can still help them, for it has the same power as the magnet of attracting iron. So mariners attach an iron needle to a piece of cork and rub it with a black lodestone. The cork and needle are then put into water, and never fail to point to the north.
(5) Brunetto Latini, writing about 1260, tells how Roger Bacon showed him[[289]] a magnet, a stone black and ugly, and explained its use. If one rubbed a needle with it, and then put the needle, fixed to a straw, in water, the point of the needle always turned towards "the Star." By this the sailor could hold a straight course, whether the stars were visible or no.
(6) In the Landnamabok, or Icelandic Book of Settlement, the main text of which was finished before 1148, there occurs a passage, probably added about 1300,[[290]] which describes a voyage of the ninth century (c. 868) to Iceland, and explains the use of ravens to direct this early course—"for at that time the sailors of the northern countries had not yet any lodestone."
(7) The Arabic author of the Baïlak el Kibjaki, or "Handbook for Merchants in the Science of Stones," relates how, in 1242, on a voyage from Tripoli to Alexandria, he himself witnessed the use of the polarized needle. He adds that Moslem merchants sailing to India, instead of the magnet-needle attached to a straw, tube or cork, used a hollow iron fish which, thrown into water, pointed north and south.
"Subsequently the instrument was improved by degrees, till it assumed the shape of a box, containing a needle moving freely on a metal point, and covered by a compass-rose." It is here probably that the share of Amalfi is to be found,[[291]] and it may have been Flavio Gioja, or some other citizen of the oldest commercial republic of Italy, who first fitted the magnet into the box, and connected it with the compass-card, thus making it generally and easily available.[[292]]