48 



EXPERIMENTAL GENERAL SCIENCE 



ing and in time it is probable that it will completely displace 

 the Fahrenheit scale. It is to be noted that the differences in 

 these two scales are not differences in temperature but merely 



differences in methods of measuring. 

 Thirty-two degrees above zero Fah- 

 renheit (32F.) is the same as zero 

 Centigrade (0C.). Thermometers 

 are frequently made with both scales 

 marked on them. 



48. Absolute Zero. The maker of 

 the Fahrenheit thermometer appears 

 to have assumed that nothing could 

 be colder than 32 degrees below the 

 ther- freezing point of water, and for this 

 reason he called that point zero. 

 Temperatures much below zero are 

 now known. Even the temperature of the air in winter in 

 the Northern States may go several degrees below this point. 



FIG. 14. Clock 

 mometer. (Tower, 

 and Turton.) 



Smith 



FIG. 16. A recording thermograph. 



It is obvious, however, that an object cannot go on losing 

 heat forever. Sooner or later the last trace of heat disap- 

 pears and all molecular motion ceases. This point is called 



