The light grew dim, then neared blackness as they continued down the steps. Gemmel didn’t produce a torch or lantern, but instead waved at Kelsier to go first. Another test of some sort?Steel burning within Kelsier let him identify sources of metal by their blue lines. He paused, then dropped the handful of coins to the ground, letting them bounce  down  the  steps.  In  falling,  they  let  him  see  where  the  stairs  were,  and when they came to a rest that gave him an even better picture.
The  blue  lines  weren’t  really  “seeing,”  and  he  still  had  to  walk  carefully.  However, the coins helped a great deal, and he did see a door latch as it drew near. Behind, he heard Gemmel grunt, and for once it seemed appreciative. “Nice trick with the coins,” the man murmured