THE THERMOMETER 335 



have seen, on a little wooden board, a glass rod 

 pierced by a very fine canal and ending at the bottom 

 in a little bulb. In the bulb is a red liquid, which 

 ascends or descends in the canal of the tube accord- 

 ini: to whether it is warmer or colder. That is 

 called a thermometer. In freezing water the red 

 liquid goes down to a point in the tube called zero; 

 in hoiling water it goes up to a point marked 100. 

 The distance between these two points is divided 

 into one hundred equal parts called degrees.'* 1 



"Why degrees?" asked Emile. 



"By that it is meant that these divisions have a 

 certain resemblance to the degrees or steps of a 

 flight of stairs, or the rounds of a ladder. The red 

 liquid goes up or down from division to division just 

 as we mount or descend a flight of stairs step by 

 step. If it grows warmer, the red liquid moves and 

 little by little climbs the steps; if colder, it goes 

 down the ladder. Thus the heat can be estimated 

 according to the step or degree where the liquid 

 stops. 



44 It is freezing when the liquid goes down to zero; 

 the heat is that of boiling water when it goes up to 

 division 100. The intermediate steps or s in- 



dicate, evidently, other states of heat, greater when 

 the degree is higher up on the ladder. 



"The degree of heat of any body, as indicated by 

 the thermometer, is called its temperature. Thus we 

 say the temperature of IVee/in-- water is zero, that 

 of boiling water one hundred decrees." 



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