656 COSMOS. 



oceanic enterprises connected with that event, so rapidly 

 exercised on the combined mass of physical and astrono- 

 mical science, is rendered most strikingly manifest, when we 

 recal the earliest impressions of those who lived at this period, 

 and the extended range of those scientific efforts, of which 

 the more important are comprehended in the first half of the 

 sixteenth century. Christopher Columbus has not only the 

 merit of being the first to discover a line without magnetic va- 

 riation, but also of having excited a taste for the study of 

 terrestrial magnetism in Europe, by means of his observations 

 on the progressive increase of western declination in rece- 

 ding from that line. The fact that almost everywhere the 

 ends of a freely moving magnetic needle, do not point ex- 

 actly to the geographical north and south poles, must have 

 repeatedly been recognised, even with very imperfect in- 

 struments, in the Mediterranean, and at all places where, 

 in the twelfth century, the declination amounted to more 

 than eight or ten degrees. But it is not improbable that 

 the Arabs or the Crusaders, who were brought in contact 

 with the east between the years 1096 and 1270, might, 

 while they spread the use of the Chinese and Indian mariner's 

 compass, also have drawn attention to the north-east and 

 iiorth-west pointing of the magnetic needle in different 

 regions of the earth, as to a long known phenomenon. We 

 learn positively from the Chinese Penthsaoyan, which was 

 written under the dynasty of Song,* between 1111 and 1117, 



* It appears to be a remarkable fact, that the earliest classical writer 

 on terrestrial magnetism, William Gilbert, who cannot be supposed to 

 have had the slightest knowledge of Chinese literature, should regard the 

 mariner's compass as a Chinese invention, which had been brought to 

 Europe by Marco Polo. " Ilia quidem pyxide nihil unquam humanis 

 excogitatum artibus humano generi profuisse magis, constat. Scientia 

 nauticse pyxidulas traducta videtur in Italiam per Paulum Venetum, 

 \ui circa annum mcclx. apud Chinas artem pyxidis didicit." (Quili- 

 elmi Gilberti Colcestrensis, Medici Londinensis de Magnete Physio- 

 loffia nova, Lond. 1600, p. 4.) The idea of the introduction of the 

 compass by Marco Polo, whose travels occurred in the interval between 

 1271 and 1295, and who, therefore, returned to Italy after the mariner's 

 compass had been mentioned as a long-known instrument by Guyot de 

 Provins in his poem, as well as by Jacques de Vitry and Dante, is not 

 supported by any evidence. Before Marco Polo set out on his travels in 

 the middle of the thirteenth century, Catalans and Basques already 

 made use of the compass. (See Raymond Lully, in the Treatise Dt 

 Contemplation*., written in 1272.) 



