Definitions for "downcast"
Cast downward; directed to the ground, from bashfulness, modesty, dejection, or guilt.
depressed; dispirited; dejected; -- of people.
directed downward; "a downcast glance"
Keywords:  mine, shaft, ventilating, air, fresh
A ventilating shaft down which the air passes in circulating through a mine.
The shaft down which fresh air passes into the workings of the mine. Most commonly also used as the winding shaft
a ventilation shaft through which air enters a mine
Keywords:  melancholy, look
Downcast or melancholy look.
Keywords:  risky, dump, wrong, core, operation
a risky operation because if you are wrong, your program will most likely core dump