132 ARCHIMEDES' PRINCIPLE. 



648 cu. cm. of water (see 228) while the upper face will be pressed 

 downward with a force represented by the weight of (6 x 6 x 12 =) 

 432 cu. cm. of water. The resultant of all these forces, therefore, 

 will be an upward pressure represented by the weight of (648 -432=) 

 216 cu. cm. of water. But 216 cu. cm. is the volume of the cube,, 

 This upward pressure or buoyant effort is exerted against the force of 

 gravity, and diminishes the weight of the cube. 



239. An Experimental Demonstration. 



This principle of Archimedes may be experimentally veri- 

 fied as follows : From one end of a scale-beam suspend a 



FIG. 80. 



cylindrical bucket of metal, I, and below that a solid cyl- 

 inder, a, which accurately fits into the bucket. Counter- 

 poise with weights in the opposite scale-pan. Imjnerse a 

 in water and the counterpoise will descend, showing that a 

 has lost some of its weight. Carefully fill b with water. 

 It will hold exactly the quantity displaced by a. Equili- 

 brium will be restored. 



