escape passages leading directly from an emergency exit doorway to the surface or other safe place.such passages are generally feasible only for tunnels with little cover (cut and cover tunnels for instance). i feel like wherever i pointed my camera kids were playing, adults were laughing and everyone was generally just having a wonderful time. dirty bird baths can become unpleasant for both birds and humans. these are especially useful for tracing this pattern onto another sheet of paper, if you want to save the original - you just mark through the holes. 