problem Navani had been trying to solve. This is working, she thought with excitement, turning off the fabrial, then having the men pull her in a third direction. Making the Fourth Bridge rise into the air had not been terribly difficult—the truly hard part had been getting it to move laterally after raising it into the air.
The secret to making the Fourth Bridge fly—and to making this handheld device work—involved a rare metal called aluminum. It was what the Fused used for weapons that could block Shardblades, but the metal didn’t just interfere with Shardblades—it interfered with all kinds of Stormlight mechanics. Interactions with it during the expedition into Aimia earlier in the year had led Navani to order experiments, and Falilar himself had made the breakthrough.
The trick was to use a specific fabrial cage, made from aluminum, around the conjoined rubies. The details were complicated, but with the proper caging, an artifabrian could make a conjoined ruby ignore motion made by the other along specific vectors or planes. So, in application, the Fourth Bridge could use two different dummy ships to move. One to go up and down, the other to go laterally.
The complexities of that excited Navani and her engineers, and had led to the new device she now wore. She could move her arm in any direction she wanted, conjoin the fabrial, then direct force through it in a specific direction.
Momentum and energy were conserved per natural conjoined fabrial mechanics. Her scientists had tested this a hundred different ways, and some applications quickly drained the fabrial—but they’d known about those from ancient experiments. Still, there were thoughts whirring in her head. There were ways they could use this to directly translate Stormlight energy into mechanical energy.
And she’d been thinking of other ways to replace the manpower needs.…
“Brightness?” Falilar said. “You seem concerned. I’m sorry if the device has more problems than you expected. It’s an early iteration.”
“Falilar, you worry too much,” Navani said. “The device is amazing.”
“But … the manpower problem…”
Navani smiled. “Come with me.”
* * *
A short time later, Navani led Falilar into a section of the twentieth floor of the tower. Here she had another team working—though this one was made up of more laborers and fewer engineers. They’d located a strange shaft, one of many odd features of the tower. This one plummeted through the tower past its basements, eventually connecting to a cavern deep beneath.
Though the original purpose of it baffled their surveyors and scientists, Navani had a plan for the shaft. It had involved setting up several steel weights here, each as heavy as three men, suspended on ropes.
She nodded to the workers as they bowed, several holding up sphere lanterns for her and the ardents as they stepped up to the deep hole, which was a good six feet across. Navani peered over the side, and Falilar joined her, gripping the railing with nervous fingers.
“How far down does it go?” he asked.
“Far past the basement,” Navani said, holding up the box he had constructed. “Let’s say that, instead of men pulling a rope, we bolted the other half of this fabrial to one of these weights. Then we could connect the device’s trigger to these pulleys at the top—so that the trigger dropped the weight.”
“You’d get your arm pulled off!” Falilar said. “You’d be yanked hard in whatever direction you’ve pointed the device.”
“Resistance on the pulley line could modulate the initial force,” Navani said. “Maybe we could make it so the strength of the trigger pull determines how fast the line is let out—and how fast you are propelled.”
“A clever application,” Falilar said, wiping his brow as he glanced at the dark shaft. “It doesn’t do anything about the manpower issue though. Someone has to get those weights back up here.”
“Captain?” Navani asked the soldier leading the crew on this floor.
“The windmills have been set up as requested,” the man said—he was missing an arm, the right sleeve of his uniform sewn up. Dalinar was always on the lookout for ways to keep his wounded officers involved in the important work of the war effort. “I’m told they’re rated for storms, though of course no device can be perfectly protected in a highstorm.”
“What’s this?” Falilar asked.
“Windmills inside steel casings,” Navani said, “with gemstones on the blades—each one conjoined with a ruby on the pulley system up above. The storm blows, and these five weights are ratcheted to the top, potential energy stored for later use.”
“Ah…” Falilar said. “Brightness, I see.…”
“Every few