54 SCIENCE OF THE MIDDLE AGES. PT. n. 



piece of round card, and marking it with north, south, east, 



and west, he fastened a magnetised needle upon it pointing 



FIG. 6. from N. to s. ; he then fastened 



the card on a piece of cork 

 and floated it in a basin of 

 water. Whichever way he 

 turned the basin the needle 

 turned the card round till the 

 N. of the needle pointed to 



Flavio's Compass floating on water. ^ ^^ ^ ^ s> ^ ^ 



south, and from the other marks on the card he could then 

 tell the direction of the west, north-west, &c. 



You will see at once how important this discovery was ; 

 for when a ship is at sea, far from land, there is nothing to 

 guide the captain except the stars, and they cannot always 

 be seen, so that before he had a compass he was obliged to 

 keep in sight of land in order to find his way. But as soon 

 as he had an instrument which pointed out to him which 

 way his ship was going, he could steer boldly and safely 

 right across the sea. 



There has been much dispute as to who first discovered 

 the compass, and some people think that the Chinese used it 

 in very early times ; but learned men now agree that Gioja 

 discovered it independently, and it is certain that he was the 

 first to use it in a ship. Of course it would have been very 

 inconvenient to have it always floating in a basin of water ; 

 so the card was fitted, by means of a little cap, on to the top 

 of a pin, round which it could turn easily, and this is the way 

 it is still made. As the king of Naples belonged at that 

 time to the royal family of France, Gioja marked the north 

 point of the needle with a fleur-de-lys in his honour, and the 

 mariner's compass of all nations still bears this mark. The 



