Page 136 of Hidden Tide

Then north again.

Nothing changes.

I look toward the windows.

Beyond them, the tide is pulling out beneath the Golden Gate Bridge.

“Current doesn’t only mean water,” Ivy says.

“It can mean electricity,” Ward replies.

“Or something happening now,” Willow adds.

“Or a flow through a wire,” Ben says.

Thomas comes closer.

“James used to repair marine compasses at my boathouse. He had a device for correcting magnetic deviation.”

“A current through an electromagnetic coil,” I say.

Ben looks at me. “You know how to use one?”

“I’m an engineer.”

“Right. Stupid question.”

“The maintenance building may have one,” Keating says. “The Coast Guard still calibrates navigation equipment.”

Marquez returns the compass to its container.

“No one experiments with it until the evidence team is present.”

For once, I don’t argue.

Twenty minutes later, we stand inside a guarded maintenance room.

A technician positions my compass within a circular calibration coil. Marquez watches every movement while another agent records the procedure.

“We’ll apply the lowest current first,” the technician says. “If there is a magnetic release inside the base, it may respond.”

“What if there isn’t?” I ask.

“Then nothing happens.”

He activates the coil.

The compass needle spins once.

Stops.

He increases the current slightly.

A soft click comes from beneath the brass base.

Everyone freezes.

“Turn it off,” Marquez orders.