Acoustic Surveillance and Perimeter Sort

A low-frequency pulse resonated through the wooden uprights of the shelf. I stabilized my stance against a hardcover spine and scanned the desk below. Visual contact with the anticipated chameleon unit remains negative. To utilize operational downtime, I began cataloging structural frequencies. Tapping the metal ring of a loose binder produced an 800-hertz chime. Nearby, three discarded brass paper fasteners lay scattered near the dust line. I shifted each pin into a uniform parallel row beside the shelf trim. The mechanical snap of brass against pine confirmed firm alignment. The perimeter is ordered. Surveillance continues.