difference in intensities of lights remained perceptible. The 

 flicker photometer screen is considered by some good authorities 

 to be susceptible of more accurate reading than any other. 



The general appearance and features of the lamps used in the 

 tests are shown in the various illustrations. Lamps Nos. i, 2 and 

 3 are gravity lamps each using a clear pearl glass chimney 1^x8 

 inches and a four-inch mantle with 3^ inches of the mantle ex- 

 posed to heat. 



Lamp No. 2 Operated successfully with alcohol and gasoline. 



Lamp No. I was an over-head generator and had an average 

 fuel head of 15^2 inches measured from center of generator to 

 center of tank. The tube in which the fuel was gasified was 

 coiled over the chimney. 



Lamp No. 2 was also an over-head generator, had a fuel head 

 of 21 inches and a straight generator tube provided with a hood 

 which seemed to aid in the absorbtion of heat by the generator 

 tube. 



Lamp No. 3 was an underneath generator with a fuel head of 



