200 OUR PHYSICAL WORLD 



a city in Ionia, a province of Greece. This lodestone is one of 

 the ores of iron, an oxide of iron, known as magnetite. They knew 

 also that a piece of iron rubbed on such a stone became a magnet. 

 We know now other and better ways of making a magnet, as 

 will appear below. 



In the city of Naples, Italy, is a monument to Flavio Gioja, 

 a man who lived in the city of Amain, and the legend on the 

 monument ascribes to him the discovery of the compass in the 

 year 1302. This is undoubtedly an error, for Peter de Maricourt, 

 a Frenchman, also known as Peregrinus, had devised a compass 

 with pivoted needle and graduated scale as early as 1269, and 

 mention is made of it in cruder form nearly a hundred years 

 earlier. This primitive compass consisted of a magnetized 

 needle that floated on a cork in a basin of water. Gioja did 

 make improvements in the compass. At that time there was no 

 Italy. Amain, once an independent republic, then belonged to 

 the kingdom of Naples, whose ruler was of the royal family of 

 France. So Gioja marked the north-pointing end of his compass 

 needle with the fleur-de-lis, symbol of the iris, the flower of 

 France that appears on her coat-of-arms. It still is usually so 

 marked. 



Amain was once a great center of commerce whose ships ruled 

 the Mediterranean and brought her great wealth. Now the 

 stone wharves where her ships unloaded are lying below the 

 sea, due to a submergence of that portion of the coast. Her 

 prestige is gone. Still she will long be remembered, for the 

 compass which came from her in its improved form was a boon 

 to commerce. By it a vessel finds its way from port to port 

 even when clouds obscure the stars and the mariner has no guide 

 but the little steadfast needle. 



The end of the magnet that points north when the magnet 

 is freely suspended is called the north pole and the other end the 

 south pole. When two such magnets are brought together end 

 to end, they repel each other if the poles are alike, but attract if 

 they are unlike. This fact may readily be discovered by any 



