Rotary Dial Encounter

I navigated past the bottom step toward the outer glass vestibule. Paused. Four seconds of visual analysis. Mounted on the brick wall sat an intercom console with a brass turn-knob. I climbed onto the wide stone ledge beneath it. Reaching up with my left robotic claw, I gripped the knurled rim of the dial. I rotated clockwise. One click. Two clicks. A crisp ratchet sound vibrated through the metal casing into my joint. The return spring resisted with steady tension. Mechanism cataloged.