HISTORY OF DISCOVERY RELATIVE TO MAGNETISM. 291 



the year 868 Foke Vilgerdarson, tbe third discoverer of this island, a noted 

 pirate, sailed from llogalaud, in Norway, in search of Iceland, or Gardarsholm, 

 as it was then called, and took with him as pilots three ravens. To consecrate 

 these to their important pnrpose, he instituted a grand sacrificial ceremony at 

 Smoersund,' when his ship was at anchor ready to sail; for, says Are Frode, the 

 seamen in the northern regions were as yet unacquainted with the use of the lead- 

 ing stone. By the term leading stone the writer designated the natural magnet, 

 which, in English, is still called loadstone or Icadstone. It may, however, be 

 presumed, from this form of (expression, that in Frode's time the compass pro- 

 perly was not yet known, but that the natural magnet was suspended by a 

 thread. According to the testimony of Hansteen, mention is made of the leidar- 

 Btone or solar-stone, in the vSturhinga Saga. Gilbert, in his celebrated work 

 "De Magneto," relates that, according to the report of Flavins Blondus, the 

 Amalfitanes (Amalfis?) in Naples, first, about the year 1300, constructed and 

 applied the mariner's compass, and this according to the direction of John 

 Gioja, one of their fellow-citizens. He presumes, however, that more probably 

 the knowledge of this compass had been brought from China to Italy, by Paul 

 Venetus, about the year 1260. Gioja, of Amalfi, was, nevertheless, at least the 

 first who- placed the magnetic needle on a point, and divided the compass, ac- 

 cording to the points of the horizon, into eight divisions. 



That the mariner's compass, however, was known at an earlier period in the 

 south of Europe, although in a rude form, is evident from a passage of a satirical 

 poem, which was published by Guyot de Provins in 1203, and of which the 

 original manuscript is still preserved in the royal (imperial) library at Paris. 

 It is mentioned in this poem that the seaman easily finds the northern direction 

 by the assistance of an ugly, black stone, called mariniere, and this even under 

 a cloudy sky ; that for this purpose it was only necessary to rub a needle with 

 the stone, and then, attaching the former to a straw, allow it to swim on 

 water, when it Avould point to the north. Cardinal Vitri, who lived about the 

 year 1200, also makes mention of the magnetic needle in his history of Jerusa- 

 lem, and remarks, moreover, that it is of inestimable value to mai-iners. 



That the mariner's compass was known to northern nations is evident from 

 the history of Norway, by Torfceus, in which it is stated therein that Yarl 

 Stula was rcAvarded with a compass for a poem written on the death of the 

 Swedish coiint Byrgeres. The directive force of the magnet is also distinctly 

 alluded to in a letter to Peter Peregrinus de Marcourt, which was written 

 towards the end of the thirteenth century. This letter was directed to " Sige- 

 rius de Foucancoui-t, a soldier in the service of magnetism," and contains a de- 

 scription of the magnet, of the means to find its poles, and of its peculiar 

 attractive property in regard to iron, and finally proves that the extremity of 

 the magnet which turns towards the north is attracted by the one that tm-ns 

 towards the south. One of the oldest treatises on magnetism is contained in a 

 Latin manuscript of Peter Alsiger, which is found in the University library at 

 Leyden, and was written in 1269. This manuscript, which seems to have been 

 composed for the instruction of a friend, is divided into two parts, of which the 

 first contains ten, and the second three, chapters. In the second chapter of the 

 second part the mariner's compass is distinctly and perfectly described ; and 

 what is still more interesting, the author does not only mention the variation 

 of the magnetic needle from the true north pole, but also gives an account of 

 the accurate observations which he had made in regard to the amount of this 

 deviation. " Observe well," says he, " that the ends of the magnet, and those 

 of the needle rubbed with it, do not accm-ately turn toward the poles, but that 

 the end which points toward the south inclines somewhat to the west, and the 

 one pointing to the north in an equal proportion to the east." The magnitude 

 of this deviation amounts, according to numerous observations, to five degrees. 



