180 FERGUSON'S LECTURES. 



LECT that any other body of equal weight, and of less bulk 

 V _^T^^ than himself, could not have raised the water so high its 

 he did ; he immediately told the king, that he had found 

 a method by which he could discover whether there were 

 any cheat in the crown. For, since gold is the heaviest 

 of all known metals, it must be of less bulk, according 

 to its weight, than any other metal. And therefore he 

 desired that a mass of pure gold, equally heavy with 

 the crown when weighed in air, should be weighed 

 against it in water ; and if the crown was not alloyed, 

 it would counterpoise the mass of gold, when they were 

 both immersed in water, as well as as it did when they 

 were weighed in air. But upon making the trial, he 

 found that the mass of gold weighed much heavier in 

 water than the crown did. And not only so, but that, 

 when the mass and crown were immersed separately in 

 one vessel of water, the crown raised the water much 

 higher than the mass did ; which shewed it to be alloyed 

 with some lighter metal that increased its bulk. And 

 so, by making trials with different metals, all equally 

 heavy with the crown when weighed in air, he found 

 out the quantity of alloy in the crown. 



The specific gravities of bodies are as their weights, 

 bulk for bulk ; thus a body is said to have two or three 

 times the specific gravity of another, when it contains 

 two or three times as much matter in the same space. 



A body immersed in a fluid will sink to the bottom, 

 if it be heavier than its bulk of the fluid. If it be sus- 

 pended therein, it will lose as much of what it weighed 

 in air, as its bulk of the fluid weighs. Hence, all bo- 

 dies of equal bulks, which would sink in fluids, lose equal 

 weights when suspended therein. And unequal bodies 

 lose in proportion to their bulks. 



Th e The hydrostatic balance differs very little from a com- 



hydrostatic mon balance that is nicely made : only it has a hook at 



the bottom of each scale, on which small weights may 



