Extra qn. answers....

Since copper is a good conductor of heat, the space in between the copper gauze will have a higher temperature than the surroundings. The higher temperature inside is also due to the presence of the candle. When the surrounding temperature almost reach the ignition temperature of the methane, the methane in between the copper gauze will burn first. This is because the space inside the copper gauze have a slightly higher temperature. Thus, this will warn the miners to run out of the mine quickly and SAVE THEMSELVEs!!!!

Extra qn....

The figure shows a miner's safety lamp invented by Sir Humphry Davy. How does the copper gauze act as a safety device to prevent explotions if a flammable gas such as methane is present in the mine? (Hint: Copper is a good conductor of heat. Methane will burn only if the surroundings reach its ignition temperature.)