THE THERMOMETER. 



59 



continent of Europe, and by scientific men all over 

 the world. 



131. FAHRENHEIT THERMOMETER. This 



Describe the . 



Fahrenheit is the thermometer in common use in this 

 thermometer. country . The i ristr ument itself is pre- 

 cisely the same as the centigrade. The difference is 

 only in the graduation. In graduating it, the space 

 between the freezing and boiling points having been 

 marked on the glass, is divided into one hundred and 

 eighty parts, and the rest of the tube, above and below, 

 into similar spaces. The zero, or starting point, is 

 fixed lower down than in the centigrade, 

 where nothing especial happens, instead of 

 where water freezes. The consequence is, 

 that in counting up and affixing the numbers? 

 the freezing point comes at 32, and the 

 boiling point at 212. There is no good rea- 

 son for placing the zero there, or for qhoosing 

 such a number as 180 for the number of de- 

 grees between freezing and boiling. The 

 centigrade graduation is, therefore, much to 

 be preferred. If a thermometer of each 

 kind were immersed in boiling water, the 

 mercury would rise in the centigrade to the 

 point marked 100, and in the Fahrenheit *^ ^^ 

 to the point marked 212. In the same way,^ero cen- 

 tigrade corresponds to 32 Fahrenheit. The two ther- 

 mometers are compared in the figure. 



ff oio is extreme 132. EXTREME COLD, HOW MEASURED. 



coidmeasurcd? AS the temperature is lowered, the mer- 

 cury of the Fahrenheit thermometer sinks, until by 



