Hydrostatics. 45 



half heavier than its bulk of water, and conse- 

 quently loses more than one-nineteenth of its 

 weight in that fluid. 



This mode of ascertaining the standard value 

 of metals was invented by the famous philosopher 

 Archimedes, who made use of it to detect a fraud 

 in the golden crown of Hiero, king of Syracuse. 

 This king had given a certain weight of gold to 

 be made, by a goldsmith of that place, into a 

 crown ; the weight of the crown was exactly the 

 same as the weight of the gold he had received ; 

 but Hiero still suspecting an imposition, Archi- 

 medes was requested to detect the fraud ; and he 

 was led to make the trial in this way, without 

 melting the crown, or destroying the workman- 

 ship, from the resistance which he found was 

 made by the water to his own body upon his 

 going into the bath. A quantity of fine gold was 

 therefore brought, and equally balanced in a 

 scale against the crown ; but when both came to 

 be weighed in water, it was found that the crown 

 was much lighter ; whence not a doubt could re- 

 main but that it was made of adulterated metal. 



It is upon the same principles that the density 

 of different fluids is put to the test. It might, 

 it is true, be ascertained by weighing them 

 against each other in different scales ; but it may 

 be done in a more easy and expeditious manner 

 upon the hydrostatic plan, since the same body 

 that will sink in one fluid will swim in another, 

 and the same body will sink to different depths in 



