The Mark of Athena

“I guess,” Leo said. “But this workmanship…no offense to you Camp Jupiter types, but this is too complicated to be Roman.”

Frank snorted. “Whereas you Greeks just love making things complicated.”

“Hey,” Leo protested. “All I’m saying is this machinery is delicate, sophisticated. It reminds me of…” Leo stared at the sphere, trying to recall where he’d read or heard about a similar ancient machine. “It’s a more advanced sort of lock,” he decided. “You line up the symbols on the different rings in the right order, and that opens the door.”

“But what’s the right order?” Hazel asked.

“Good question. Greek spheres…astronomy, geometry…” Leo got a warm feeling inside. “Oh, no way. I wonder…What’s the value of pi?”

Frank frowned. “What kind of pie?”

“He means the number,” Hazel guessed. “I learned that in math class once, but—”

“It’s used to measure circles,” Leo said. “This sphere, if it’s made by the guy I’m thinking of…”

Hazel and Frank both stared at him blankly.

“Never mind,” Leo said. “I’m pretty sure pi is, uh, 3.1415 blah blah blah. The number goes on forever, but the sphere has only five rings, so that should be enough, if I’m right.”

“And if you’re not?” Frank asked.

“Well, then, Leo fall down, go boom. Let’s find out!”

He turned the rings, starting on the outside and moving in. He ignored the zodiac signs and letters, lining up the correct numbers so they made the value of pi. Nothing happened.

“I’m stupid,” Leo mumbled. “Pi would expand outward, because it’s infinite.”

He reversed the order of the numbers, starting in the center and working toward the edge. When he aligned the last ring, something inside the sphere clicked. The door swung open.

Leo beamed at his friends. “That, good people, is how we do things in Leo World. Come on in!”

“I hate Leo World,” Frank muttered.

Hazel laughed.

Inside was enough cool stuff to keep Leo busy for years. The room was about the size of the forge back at Camp Half-Blood, with bronze-topped worktables along the walls, and baskets full of ancient metalworking tools. Dozens of bronze and gold spheres like steampunk basketballs sat around in various stages of disassembly. Loose gears and wiring littered the floor. Thick metal cables ran from each table toward the back of the room, where there was an enclosed loft like a theater’s sound booth. Stairs led up to the booth on either side. All the cables seemed to run into it. Next to the stairs on the left, a row of cubbyholes was filled with leather cylinders—probably ancient scroll cases.

Leo was about to head toward the tables when he glanced to his left and nearly jumped out of his shoes. Flanking the doorway were two armored manikins—like skeletal scarecrows made from bronze pipes, outfitted with full suits of Roman armor, shield and sword.

“Dude.” Leo walked up to one. “These would be awesome if they worked.”

Frank edged away from the manikins. “Those things are going to come alive and attack us, aren’t they?”

Leo laughed. “Not a chance. They aren’t complete.” He tapped the nearest manikin’s neck, where loose copper wires sprouted from underneath its breastplate. “Look, the head’s wiring has been disconnected. And here, at the elbow, the pulley system for this joint is out of alignment. My guess? The Romans were trying to duplicate a Greek design, but they didn’t have the skill.”

Hazel arched her eyebrows. “The Romans weren’t good enough at being complicated, I suppose.”

“Or delicate,” Frank added. “Or sophisticated.”

“Hey, I just call it like I see it.” Leo jiggled the manikin’s head, making it nod like it was agreeing with him. “Still…a pretty impressive try. I’ve heard legends that the Romans confiscated the writings of Archimedes, but —”

“Archimedes?” Hazel looked baffled. “Wasn’t he an ancient mathematician or something?”

Leo laughed. “He was a lot more than that. He was only the most famous son of Hephaestus who ever lived.”

Frank scratched his ear. “I’ve heard his name before, but how can you be sure this manikin is his design?”

“It has to be!” Leo said. “Look, I’ve read all about Archimedes. He’s a hero to Cabin Nine. The dude was Greek, right? He lived in one of the Greek colonies in southern Italy, back before Rome got all huge and took over. Finally the Romans moved in and destroyed his city. The Roman general wanted to spare Archimedes, because he was so valuable—sort of like the Einstein of the ancient world—but some stupid Roman soldier killed him.”

“There you go again,” Hazel muttered. “Stupid and Roman don’t always go together, Leo.”

Frank grunted agreement. “How do you know all this, anyway?” he demanded. “Is there a Spanish tour guide around here?”

“No, man,” Leo said. “You can’t be a demigod who’s into building stuff and not know about Archimedes. The guy was seriously elite. He calculated the value of pi. He did all this math stuff we still use for engineering. He invented a hydraulic screw that could move water through pipes.”

Hazel scowled. “A hydraulic screw. Excuse me for not knowing about that awesome achievement.”