SPECIFIC GkAVITY OF BODIES. 61 



Archimedes, in the following manner. Hifero, king of Sy- 

 racuse, having given to a workman a quantity of pure gold, 

 of which to make a crown, suspected that the artist had kept 

 part of the gold, and adulterated the crown with a baser 

 metal. The king applied to Archimedes to discover the 

 fraud. The philosopher long studied it in vain, and at length 

 accidentally hit upon a method of verifying the king's sus- 

 picion. Going one day into a bath, he took notice that the 

 water rose in the bath, and immediately reflected that any 

 body, of equal bulk with himself, would have raised the water 

 just as much ; though a body of equal weight, but not of 

 equal bulk, would not raise it so much. From this idea he 

 conceived a mode of finding out what he so much wished, 

 and was so transported with joy, that he ran out of the bath, 

 crying out in the Greek tongue, " I have found it, I have 

 found it !" 



Now, since gold was the heaviest of all metals known to 

 Archimedes, it occurred to him that it must be of less bulk, 

 according to its weight, than any other metal ; and he, there- 

 fore, desired that a mass of pure gold, equally heavy with 

 the crown when weighed in air, should be weighed against 

 it in water, conjecturing that if the crown was not alloyed, 

 it would counterpoise the mass of gold when they were both 

 immersed in water, as well as it did when they were weighed 

 in air. But upon making trial, it was found that the mass 

 of gold weighed much heavier in water than the crown did : 

 nor was this all — when the mass and crown were immersed 

 separately in the same vessel of water, the crown raised the 

 water much higher than the mass did ; which showed it to 

 be alloyed with some lighter metal that increased its bulk. 

 And upon this principle is the doctrine of the specific gravi- 

 ties of bodies founded. 



Questions. — 1. What is meant by the specific gravities of bodies i* 

 2. What is said of a body immersed in a fluid ? 3. What is the gene- 

 ral rule for finding the specific gravity of a solid heavier than water ? 

 4. What example is given ? 5. How may a piece of gold be tried ? 

 6. Why do vessels float ? 7. What incident led to the method of dis- 

 covering the specific gravities of bodies ? 8. Who made the disco- 

 very, and how ? 9. Explain the method and the result. 10. Explain 

 by fig. 14. the use of the hydrostatic balance. 11. Describe the hy* 

 droineter. 



