Temperature. Thermometers 137 



of mercury. When the thermometer is placed in 

 contact with a body hotter, than itself, heat is given 

 up to the thermometer by the hot body, and the 

 mercury expands and hence rises in the tube. On the 

 other hand, when brought into contact with a body 

 colder than itself, the thermometer gives up heat to 

 the body, with the result that the volume of the mercury 

 becomes less and the thread of liquid in the tube sinks. 



Fig. 39. 



The method of construction of a thermometer is 

 of interest since it introduces some applications of 

 principles previously investigated. The making of a 

 mercury thermometer is too delicate an operation for 

 general practice, but the method is similar to that 

 described in the next experiment dealing with the 

 construction of an alcohol thermometer. 



EXPERIMENT 46. A piece of thick- walled glass 

 tubing of fine bore usually called " capillary tubing " 



