EXPANSION BY HEAT. 263 



against a lever or index (h) near to its centre, this lever in turn 



Fig. 117. Bar and Gauge 

 Fig. 116. Ring and Ball (expansion). (expansion). 



pressing upon a second (p). When the bar is heated by a large 



Fig. 118. Measurement of Expansion (bar), 

 flame of spirit underneath it grows longer, and consequently 



