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In my time spent in coal mining a battery permitted for use underground was one which was made up of a maximum of sixteen - three pint capacity porous pot type Leclanche cells. This battery able to produce a current not exceeding 1.6 amps at avoltage not exceeding 25 volt. This type of battery had been shown to be safe by laboratory tests. The battery was used to supply bell signalling circuits and the bells had to be of an approved type with internal components to counteract the inductive energy of the bell coils. There was an 'approved' dry battery available, having exposed terminals and again intended for signalling systems. The battery incorporated intermal non-inductive resistors to reduce the current to a maximum of 1.6 amps. Batteries were also used in telephones and shot-firing exploders and again they were generally of an approved type. The batteries for shot-firing had to be renewed after a few months of use. At that time oxy-acetylene burning was permitted, by special licence and this generally took place on a Saturday morning after the majority of men had left the pit as a maximum of eight men were allowed in the pit. A good example of where oxy-acetylene burning was used was in building up batteries for battery operated locos when the connecting straps between cells were welded in place. Alan Vickers.