Miscellaneoics Tables, Figures a?id Notes. 131 



4. Thermometer Scales. 



Fahrenheit. — The freezing-point is taken as the 32d. degree of 

 the scale, and ISO degrees are made between that and the boiling- 

 point, which therefore becomes 212°. 



Centigrade or Celsius. — The freezing-point of water is taken as 

 zero, and boiling-point as 100°. 



Reaumur. — The freezing-point of water is taken as zero, the 

 boiling-point as 80°. 



A degree Centigrade is therefore greater than a degree of 

 Fahrenheit as nine is greater than five ; and a degree of Reau- 

 mur is greater, as nine is greater than four. 



To reduce Fahrenheit degrees to Centigrade, subtract 32 from 

 the given degree of Fahrenheit and multiply the remainder by 5 

 and divide it by 9 : (F.°— 32) f . 



To reduce Centigrade to Fahrenheit, multiply the given degree 

 of Centigrade by 9 and divide the product by 5, then to the quo- 

 tient add 32: (fC.°+32). 



To reduce Fahrenheit to Reaumur, subtract 32 from the given 

 degree of Fahrenheit and multiply the remainder by 4 and divide 

 by 9: (F.°— 32)}. 



To reduce Reaumur to Fahrenheit, multiply the given degree of 

 Reaumur by 9 and divide by 4, then add 32 : (|R.° -f- 32) . 



5. Effects of Wind in Cooling Glass. 



(Leuchars.) 



Velocity of Wind Time required to lower Temperature 



per hour. from 120 to 100 Fahr. 



3.26 miles 2:58 minutes. 



5.18 " 2:16 



6.54 " . 1:91 



8.86 " 1:66 " 



10.90 " 1:50 " 



13.36 " 1:25 " 



17.97 " 1:08 11 



20.45 " 1:00 



24.54 " :91 " 



27.27 " -.81 " 



