16 Additional Remarks on the 



rate, also more easily compared with others, and their 

 researches greatly facilitated. Glass tubes being unfit 

 to measure high degrees of temperature, Mr. Wedg- 

 wood's thermometer of baked clay proves a happy 

 invention, which was much wanted. 130 degrees of 

 Fahrenheit's being equal to one of Wedgwood's, ac- 

 cording to this proportion, Mr. Wedgwood has car- 

 ried Fahrenheit's scale to the top of his own. Hence 

 a scale of heat can now be given, from the highest 

 degree yielded by a wind-furnace, to the greatest de- 

 gree of cold yet known, or produced by art. 



Of the remarkable degrees of temperature between 

 these extreme points, the following instances may not 

 prove unacceptable to such as are curious in metal- 

 lurgy or experimental chemistry : 



Fahrenheit's Wedgwood's 

 scale. scale. 



Extremity of Wedgwood's scale 32,277 240 



Greatest heat of his small air-furnace 21,877 160 



Cast iron melts - 17,977 130 

 Greatest heat of a common smith's 



forge - - - 17, 327 125 



Welding-heat of iron, greatest 13,427 95 



Fine gold melts - 5,237 32 



Fine silver melts - 4,717 28 



Swedish copper melts - 4,587 27 



Brass melts - , 3,807 21 

 Heat by which his enamel colours 



are burnt in - - 1,857 6 



Red heat, fully visible in day-light 1,077 



