MEASUREMENT OF TEMPERATURE 



29 



The bulb of the thermometer is then surrounded 

 with melting ice and left until the mercury in the 

 tube comes to a standstill. This point on the tube is 

 marked 0, the freezing point 

 of water. Likewise the bulb 

 is suspended in the steam aris- 

 ing from boiling water in a 

 flask and the point on the tube 

 at which the mercury comes 

 to rest is marked 100, the 

 boiling point of water. The 

 intervening distance on the 

 tube is divided into 100 equal 

 parts called degrees. Divi- 

 sions of the same length are 



Fig. 17. Method of deter- 

 mining the lower fixed point 

 on a thermometer. 



extended above 100 C. and 

 below 0C. 



The Fahrenheit thermom- 

 eter is similarly constructed, 

 with the freezing point of 

 water marked 32 and the 

 boiling point of water 212. 

 The intervening space on the 

 stem is divided into 180 equal 

 divisions. 



Fig. 18. Method of deter- 

 mining the boiling point. 



