235 



centimeters. With such a spring it is seen that a load of .002 grams will 

 cause an elongation of .1 of a millimeter. 



The following tables of data and results obtained by using this simple 

 Jolly balance are self explanatory. They are given not because of any 

 new principle contained in them, but because of the extreme accuracy 

 shown— accuracy seemingly out of all proportion to the care with which 

 the apparatus was constructed. 



Modulus =L/E=. 193. Mean 6.180 



Density of a Steel Bicycle Ball. 

 No Load. Load. Elongation. 



54.97 cm. 83.95 cm. 28.98 cm. 



54.97 83.93 28.96 



56.00 83.97 28.97 



Mean elongation = 28.97. 



Mass = elongation X modulus = 6.591 g. 



Diameter by micrometer screw caliper = 1.1115 cm. 



Volume .7189 cc. 



Density = M/ V = 7.78 g. per cc. 



Principle of Archimedes. 

 Ball in Air, Ball in Water. Decrease. 



82.98 cm. 79.32 cm. 3.66 cm. 



82.99 79.30 3.69 

 83.00 79.34 3.66 



Mean decrease in elongation =: 3.67 



Loss of weight in water .708 g. 



Volume of ball from preceding experiment .718 cc. 



Volume of water displaced by the ball .718 cc. 



"Weight of water displaced by the ball .718 g. 



