Describe how Andy and his team make the cartridge.

From the text:

They used the old-fashioned blasting-powder and time-fuse. They’d make a sausage or cartridge of blasting-powder in a skin of strong calico or canvas, the mouth sewn and bound round the end of the fuse; they’d dip the cartridge in melted tallow to make it water-tight, get the drill-hole as dry as possible, drop in the cartridge with some dry dust, and wad and ram with stiff clay and broken brick. Then they’d light the fuse and get out of the hole and wait.