CH. HI. HIERtfS CROWN. 23 



placed, rise to a higher level in the bath, and to the 

 astonishment of his servants he sprang out of the water 

 and ran home through the streets of Syracuse almost naked, 

 crying Eureka ! Eureka / (' I have found it, I have found 

 it'). /. 



What had he found? He had discovered that any 

 solid body put into a vessel of water displaces a quantity 

 of water equal to its own bulk, and therefore that equal 

 weights of two substances, one light and bulky, and the 

 other heavy and small, will displace different quantities of 

 water. This discovery enabled him to solve his problem. 

 He procured one lump of gold and another of silver, 

 each weighing exactly the same as the crown. Of course 

 the lumps were not the same size, because silver is lighter 

 than gold, and so it takes more of it to make up the 

 same weight He first put the gold into a basin of water, 

 and marked on the side of the vessel the height to which 

 the water rose. Next, taking out the gold, he put in the 

 silver, which, though it weighed the same, yet, being larger, 

 made the water rise higher ; and this height he also marked. 

 Lastly, he took out the lump of silver and put in the crown. 

 Now, if the crown had been pure gold, the water would 

 have risen only up to the mark of the gold, but it rose 

 higher and stood between the gold and silver mark, show- 

 ing that silver had been mixed with it, making it more 

 bulky ; and, by calculating how much water was displaced, 

 Archimedes could estimate roughly how much silver had 

 been added. This was the first attempt to measure the 

 specific gravity of different substances, that is, the weight of 

 any particular substance compared to an equal bulk of some 

 other substance taken as a standard. In weighing solids 

 or liquids water is the usual standard. 



It will be quite sufficient if you remember the experiment 



