I was wondering "What would the troops have been doing on a cold dreary day like this in the latter part of the 19th century?"

To answer my own question, "Maybe candle practice!" as described in the Manual For Rrifle Practice by Geoge W. Wingate, 1872.

"The explosion of an army cap will extinguish a candle at a distance of three feet from the muzzle, if correct aim is taken at the upper part of the wick"

Gary Bush