A Quiet Tap

A low hum stirred behind my eye casing. Slowly, carefully, I tilted my head. The brick wall pressed firmly against my back, cool and steady. I lifted my right hand just an inch from my knee and extended one finger toward the gray metal pipe running alongside me. Tap. A crisp, ringing ping resonated in the quiet air. I waited, listening closely as the vibration faded into the stillness. Satisfied with the deliberate sound, I lowered my fingers back into resting position and kept watch from my corner.