Why would so many women miners prefer to work in the mines without clothing? Why did the women need the heavy belts around their waists and chains between their legs?

2 answers

Read these very descriptive sites.

http://www.womeninworldhistory.com/coalMine.html

http://www.historylearningsite.co.uk/coal_mines_industrial_revolution.htm
They would need to work in the mines without clothing because the conditions were poor and time was being wasted a lot for them "dressing up". They needed heavy belts around their waists and chains between their legs so they could take the corves (wagons) out of the mines.