One of the Legendary Watchers

One of the main tools of the Department of Extranatural Affairs, featured in many of the Tales from the Bureau of Shadows. Described thus in Capitulation:

She opened a glass box in the main exhibit and pulled out a silvery object. "Now this is a lovely thing."

          Lovett came to her side and bent his head to examine what she held, cradled with care in her wrinkly hand. It looked like a thick, old-fashioned pocket watch, etched and knurled to within an inch of its life. He could just make out, in the middle of the elaborate swirls, the letters D-E-A.

          He looked up at her.

          "It's a watch."

          "It's a watcher," she corrected him proudly. "One of the only three still in existence." She pushed the knob, popping it open, and raised it higher for him to examine. She looked at him intently, to analyze his reaction.

          "Okay, so it's a compass." He shrugged.

          "Sir, it's a needle of gold and silver alloy, floating on a pool of pure mercury! It is totally non-magnetic. It only responds to spiritual disturbances."

When Lovett later revamps the Department, he has many other new watchers made.