PRESIDENTIAL ADDRESS. SECTION' A. I5 



need only quote one — from " The Arabian Nights." There 

 we read : — 



" To-morrow we shall arrive at a mountain of black stone called lodestone ; 

 the current is now bearing us violently towards it, and the ships will fall in 

 pieces and every nail in them will fly to the mountain and adhere to it."* 



The references to the magnet in the writings of the ancients 

 further show that the writers were aware that the attraction 

 was confined to iron; or, at any rate, it was not indiscriminate. 

 They knew also that the magnet had the power of communicat- 

 ing this power to other bodies. Of course, there were 

 many properties attributed to the magnet which have since 

 been found to rest on great imaginative power, rather 

 than on fact. We find it stated, for example, that 

 the magnet attracts flesh, that it is effective in the cure of 

 disease, that it cures baldness, that it affects the brain, that it 

 acts as a love philtre, that it loses its power when rubbed with 

 garlic, and many other equally imaginative statements. 



At what date the directive property of a magnet was first 

 discovered is not recorded. It is almost certain that it was 

 known to the Chinese before the beginning of the Christian 

 Era. In various writings there are descriptions of the so-called 

 south-pointing carts, of which the distinctive feature was a doll 

 with outstretched arm, attached to a pivoted magnet, which 

 always caused the arm to point to the south. In Evirope the 

 knowledge of the directive power was acquired much later; 

 from a careful examination of more than seventy Greek and 

 Latin authors, covering the period from the sixth century B.C. 

 to the tenth century A.D., no mention of the directive powers 

 of the lodestone has been discovered;! the first European 

 writer who refers to it and to the use of a compass 

 is Neckam, who wrote about the end of the twelfth 

 century. By the middle of the thirteenth century a more 

 exact knowledge prevailed, and the following summary of 

 the magnetic phenomena, described by Peter Peregrinus,. 

 shows how much was known at that date. Peter wrote, on the 

 I2tli of August. 1269, from the trenches at the Siege of Lucera. 

 He explains how a magnet, when divided into two parts, results 

 in two halves, each of which has two poles; how the one pole 

 of a magnet always points to the south, and the other to the 

 north; he gives a description of the mariner's compass, which 

 in its essentials is the same as the one in use to-day; he points 

 out also that the directive power of the magnet entails the 

 existence of something outside the magnet; he himself main- 

 tained that the directive power of the magnet was due to a 

 certain region of the heavens; there were other explanations 

 advanced, however, in those times, one attributing the directive 

 power to the attraction of magnetic mountains near the earth's 

 pole, and another which gave the Pole star as the cause. 



The next discovery was that of the magnetic declination. In 

 recent vears Hellmann and \\'olkenhauer have shown that this 



*Benjamin : op. cit., p. 96. 



t Terrestrial Magnetism, Vol. VIII., p. 177 



