Jack took it for a joke until Eliza agreed to scurry down the tunnel without hesitation – which meant that according to Rules that applied even to Vagabonds, Jack had to do it first, in order to scout for danger. The Doctor told him that the pieces of ox-hide were called arsch-leders, which was self-explanatory, so Jack put one on. The Doctor then demonstrated the use of the planks, which miners used to protect elbows and forearms from the stony floor when creeping along on their sides. All of this settled, Jack lay down on the floor and crept into it, wielding the plank with one arm and the kienspan with the other. He found it reasonably easy going as long as he didn't think about . . . well, about anything.