Night Anchor

The draft through the right conduit grew sharper as night deepened above. Pushing into an unknown channel in the dark wasn't practical. I knelt at the stone junction dividing the two pipes and cleared a flat patch of silt with the broken ruler. Taking the green marble, I pressed it into the center of the folded yellow card, using the crease as a stable brake so it wouldn't roll down the grade. I laid the acrylic piece across the opening as an alignment stop, then wedged my back against the curved masonry wall. The subterranean air holds steady. A solid bivouac before moving forward.