A man's head appeared through the open hatch atop the hull. "All is ready," he reported.
"Good luck, Tyrophanes!" Selene cried.
"Then launch!" Chilo called. Slaves wielding sledgehammers knocked the chocks free and the bizarre boat slid down the greased skids to enter the water with a restrained splash. It settled so deeply that Marcus feared that it would sink, but as it lost way it floated with about a foot of its upper surface still above water. With a wave and a grin, the captain of the vessel disappeared inside, pulling the hatch shut behind him. The bronze wheel protruding from the hatch turned as it was tightened from within against its oiled leather gasket.
"Now what?" Flaccus asked.
"Tyrophanes will open the valves in the hull to fill the water skins inside. These will provide enough weight to cause the boat to sink entirely beneath the water."
"How do they come back up?" Flaccus said, his face a little pale.
"There are screw-presses to expel the water once more and then the boat will rise," Chilo explained.
"Something about that just doesn't sound right," Flaccus protested.
"The principles of buoyancy were articulated by Archimedes himself," Chilo told him. "It is all quite elementary." But his own face was somewhat pale and grim, belying his confident words.
"There it goes!" Selene said.
While they watched, the boat subsided slowly beneath the surface of the lake. Some in the little crowd cried out, then there was only a low muttering. All stared out at the calm, unruffled waters of the lake, saying very little. This silence held for perhaps fifteen minutes.
"Well, that's that, then," Flaccus said finally. "The poor buggers have all drowned."
"There!" Selene shouted, jumping to her feet in her excitement. She was pointing to the east and everyone looked in that direction. Perhaps three hundred yards away the boat had surfaced. The hatch flew open and Tyrophanes leaped out and clasped his hands overhead like an Olympic victor. The crowd cheered as if they were at a chariot race.
"You see?" Chilo said. "I told you!" But sweat streamed from his brow and he looked as if he hadn't breathed the whole time the vessel was beneath the water.
The boat returned to the slip, running on the surface this time. Tyrophanes and the brave scholars who had taken the ride with him were cheered and congratulated. Even the slave rowers received applause.
"All right, it works," Flaccus said with poor grace. "Now how do you propose to sink an enemy ship with it?"
"That will take some work," Chilo said, beaming. "This is merely an experimental vessel, not a warship. That would have to be much larger. A ram would be the most efficient weapon."
"Ramming makes even a galley spring leaks," Marcus pointed out.
"We've been thinking more along the lines of a great iron saw on top of the vessel," Chilo said, "to rip the enemy ship open."
Marcus turned to Selene. "See if you can get the shipyards to build a diving warship to Chilo's design," Marcus said.
"I think I can do it," she said. "I have my resources."
"Excellent," Marcus said. "Now, Chilo, how about one of those flying machines you've been telling me about?"
Flaccus rolled his eyes and groaned but no one paid him any attention. Marcus, Chilo and Selene had their heads together in earnest discussion.
Marcus Scipio spent every hour he could spare at the Museum, in the newly expanded facilities of the Archimedean School. He had prevailed upon Selene to divert all the funds she could to advance the school's research into new weapons for use in the upcoming war with Carthage. She exerted herself splendidly for the best of reasons: Marcus assured her that, when the time came and Carthage was destroyed, Rome would make her true Queen of Egypt. Life was a high-stakes gamble in the Ptolemaic family and she deemed the prize worth the risk.
He no longer had to explain things or justify his actions to the rest of the Roman delegation because all had left save Flaccus. They were eager to take part in the upcoming wars and had no taste for pseudo-diplomatic service in Egypt. Pleading that they had done all the useful reconnaissance they were going to do, they had taken their leave, some for Carthage, others for Italy. They wanted in on the reconquest they knew was to come and considered Marcus Scipio and Flaccus utter fools for plodding along at this civilian work.
Marcus was certain that his work here was far more important to the future of Rome than any service he could perform as a commander of legions. He knew himself to be a fine soldier, but the legions were full of fine soldiers. Here, he could alter the course of history for all time to come.
As for Flaccus, he cared nothing at all for glory, but he liked the easy life and luxury of Egypt very much indeed. "I don't care if I never see Noricum again," he told Marcus. "As for Italy, it won't be a fit place to live in for a good many years to come. So if you like, I'll stay here and write up your dispatches for you. Just don't expect me to go back with you when you leave."
An endless stream of designs poured from the school, some of them logical, some clearly impractical, all of them intriguing. The improved catapults and ship-killers were the most prosaic. The chemical weapons were as dangerous to the experimenter as to any enemy. Chilo did not like them anyway as they did not involve his beloved principles of Archimedes.
"Mere apothecary work," he sniffed when a young man named Chares demonstrated an astonishing new explosive. Marcus was not so contemptuous. Quietly, he told Chares to continue his researches.
Work proceeded on the submersible vessel. Tyrophanes reported that the maiden voyage had not proceeded as perfectly as it had appeared to observers. When the ballast skins were filled, the vessel had descended as predicted and there was no serious leakage. The oars had worked well as propulsion. Other things had not gone so well. Controlling depth had been a problem. The plan had been to cruise at no more than a few feet beneath the surface, but more than once the vessel dived and struck the mud of the lake's bottom. Direction had been a difficulty as well. Visibility through the small port had been no more than a few feet in the murky water and steering had turned to guesswork. It had transpired that men working oars used up the air far faster than men at rest. Foul air had forced Tyrophanes to surface when he did and he then found that he was nowhere near where he had thought himself to be.
The scholars were already at work on these problems. Marcus admired their near-Roman ability to define problems and seek solutions. Most foreigners simply didn't think that way.
The man responsible for designing the oars thought he had a solution for the depth control problem: If vertical steering oars could make a ship move right or left, might horizontal steering oars not move it up or down? Chilo set him to designing such oars.
A young man from Cyprus who loved to experiment with mirrors and lenses said he could design a device that would allow the steersman to see above the water while the vessel was submerged. Marcus thought this sounded like magic, but Chilo told the boy to proceed with his experiments. This was a problem that would have to be solved if the submersible vessel was to be of any use.
"I'm not satisfied with the oars," Chilo said one day when they broke for lunch. "They work, but not well enough."
"What else is there?" Marcus asked. "Under water you don't have wind to move you, so how can you move without oars?"
"I keep thinking about the Archimedes screw," Chilo said. "The master devised it more than a hundred years ago to raise water. I think there must be some way to adapt it to move the boat. My thought is this …" He moved his hands in characteristically Greek gestures as he tried to articulate his thoughts. "As it is used, the screw is fixed in one place. When it is turned, water is forced to rise along the screw's channels until it drains from the upper end."