222 Dr Fyfe mt the Illuminating and Heating Power of 



vary in their illuminating power according to the height of 

 flame, yet they did not, when burned with the flame high, 

 come up in their illuminating power to the burners already 

 noticed. 



A ten-holed argand, for instance, when burning with a two- 

 inch flame, and consuming 2.85 feet per hour, did not give 

 so much light, in proportion to the consumpt, as the jet ; but 

 when the flame was raised till the consumpt became 3.75 feet 

 per hour, the 



Light was as 1 jet to 4.9 argand 



Consumpt, 1 ... 3.75 



And as 3.75 : 4.9 : : 1 : 1.30— Giving a gain of 80. 



The next kind of burner tried was the hat-idng. In this 

 the gas escapes by a slit instead of minute apertures ; of course 

 the quantity of gas consumed must depend very much on the 

 size of the slit. Those I employed were the bat-wings in com- 

 mon use, the slit being such as to admit a piece of watch- 

 spring. 



In the first trial the gas was burned in much smaller quan- 

 tity than the burners would allow to escape, and compared 

 with the standard jet of five inches as before. 



In the first trial. 



