1893.] A New Portable Miner s Safety-lamp. 



~FiGr. 4. Size of Lamp-flames. 



495 



. 5. Heights of Methane Flame-caps. 



O = Colza-petroleum flat flame (blue). 



G! = (luminous tip). 



B = Ash-worth's benzoline-flame (blue). 



H = Hydrogen flame, standard 10 mm. 



Hj = 15 mm. in the gas. 



H 2 = 5 mm. in the gas. 



