THE THERMOMETER 49 



ature rose the water rose in the tube, and when the 

 temperature went down the water also went down. 

 Temperature then, is the condition of warmth, high 

 temperature being very warm and low temperature very 

 cold. 



The usual thermometer is a very thin tube closed 

 at one end and with a bulb at the other end. This bulb 

 may contain mercury, sometimes called 

 quicksilver, or it may contain colored 

 alcohol. It is the mercury or alcohol in 

 the bull) which expands and pushes a tiny 

 thread of liquid up the tube. The ther- 

 mometer is marked either on the glass or 

 en the back, into divisions called degrees, 

 and these degrees are numbered from zero 

 up and down. There are two kinds of 

 markings on thermometers. The ther- 

 mometer which is used ordinarily is called 

 by the inventor's name, Fahrenheit, and 

 has the temperature of freezing water 

 marked 32 degrees, and the temperature of 

 boiling water marked 212 degrees. The 

 illustration shows a Fahrenheit thermom- 

 eter. The other thermometer is used by 

 scientists everywhere, and in many 

 foreign countries by everyone. This is 

 called the Centigrade thermometer and has 

 the freezing temperature of water marked 

 degrees and the boiling temperature of water marked 

 100 degrees. Of course the temperature of freezing 

 water is really just the same no matter what it is called, 

 just as you are the same person whether you are called by 



Elem. Sci. 4 



