THERMOMETPJC SCALES. 763 







1 R. = C., and 1 C. = R. Consequently, to 



convert any number of degrees Re'aumur into Centi- 

 grade degrees it is merely necessary to multiply them 



K 



by - ; similarly, if a number of Centigrade degrees is 



multiplied by -, we obtain the corresponding tem- 

 o 



perature in Reaumur degrees. For example, 28 R. 



= 28 x f C. = 35 C.; - 30 C. = - 30 x f R. = 

 4 5 



- 24 R. 



In England, and also in Holland and North America, 

 the thermometer scale invented by Fahrenheit is still 

 much used. In this scale the freezing point of water 

 is called 32, and the boiling point 212, the inter- 

 mediate space being thus divided into 180 equal parts. 

 The zero point of Fahrenheit's scale corresponds to 



- 17-77C. and -- 14-22 R. 



To convert a certain number of Fahrenheit degrees 

 into Centigrade or Reaumur the number 32 must first 

 be subtracted from the given number, in order that 



the degrees may count from the same point on the 



4 

 scale, and the remainder is then multiplied by - to 



u 



convert into Reaumur degrees, and by - to convert into 



y 



Centigrade degrees. Thus 149 F. = (149 - 32) - R. 



y 



= 117 x | R. = 52 R.; again, 149 F. = 117 x ^ Q- 

 = 65 C. Similarly,- 4 F. = - 36 x ;iR. = - 16 R.j 



