Ian Miller - Legatus Legionis

Then there was the engine. He recalled that his last problem had been to work out how steam could generate power. It was not that steam did not have power, for he had previously seen the results of water heated in an enclosed vessel: the subsequent explosion was quite horrifying. The problem was how to control it, and make it do something useful.

His first thought had been to reverse the principle of a small hand water pump that he had seen once before. Instead of a hand pulling the piston up and down, sucking and pushing water, the steam could come and go, pushing a piston up and down. Simple! Except that it was not that easy. Valves could easily be designed to open when they were pushed from one side, and close when pushed from the other, so the water did what was asked of it, and a hand can equally push or pull. Steam, however, would only push. The problem with the entry valve was that the steam was always pushing, so closing it to stop steam entering was difficult. Worse, if the steam closed the exit valve while it was entering, it would push even harder while it was supposed to be exiting! What could he do?

After speaking on this to Timothy, he received the laconic reply, "Use geometry."

Great! How?

"Quite simple, really," Timothy shrugged. "You need two paths, and a means of switching."

"Explain!" a frustrated Gaius muttered. But Timothy was not that interested in going further. Conceptually, the task was done.

He saluted another cohort, then glanced out at the marching legion. Not far away was a small crossroads, and a number of carts were waiting patiently. Then, as one cohort passed through, a Centurion stopped the next cohort, and waved the carts through. That, Gaius realized, could be the principle. He needed valves that could be opened and closed, and he could see how to achieve that: he needed some form of controller to switch paths at the right times. A rocker arm would do that. The valve could comprise a single path with, say, a right angle in it, and it could switch between two positions. In one configuration it would connect the steam generator with the cylinder, and in the other, achieved by turning it ninety degrees, it would connect the cylinder with the exit route. That should work. The valve would comprise a cylinder with the path through it that moved tightly inside another cylinder with connecting paths to the steam, the piston, and the exit. That would be easy until, he realized, someone had to make this contraption, and join it to the various pipes.

If the piston drove a wheel, that wheel could drive the rocker arm, as it had to be in phase. The problem now reduced itself to working out how he could make levers pull or push one or more valves into one or the other position. He quickly realized that simply fixing the valve to a lever would not do, because most of the time the valve would be closed to everything. It needed to be fully open to steam through almost all the power stroke, and fully open to the exit through the venting stroke. After some thought, he settled on a rocker arm plus a lever. The rocker arm would have a pin, and the lever would permit the pin to slide up and down a space. Accordingly, when the lever reached close to one extreme of its path, it would pull the rocker arm, which in turn would move the valve one way; when it reached the other extreme it would push the rocker arm, which would push the valve to the other position. All he had to do then was get the timing right; that would be roughly calculated, but could be adjusted later by trial and error for finer tuning. If that did not work, an alternative might be a cam; a wheel that would rotate, but because of an asymmetry, such as a groove, or a different radius, would move a switch.

Now that he had defined the problem properly, there were so many possible solutions that he had a new problem: which of these were the most likely to work? He would think about this and design something, then make a model and see if he could make a lever from a wheel move a rocker arm between two positions on a regular basis with sufficient force to turn a valve.

Eventually, the last cohort was marching down the road, and Gaius could return to his tent. He changed into less formal clothing and sat down to an early lunch of bread, cheese and fruit, then he drank some water. Sooner or later he would have to pack up this tent and leave, but that could wait. His orders were to remain in Judea, which presumably meant proceeding to Caesarea. There was no hurry; he could get started tomorrow, and leaving it for tomorrow might save him effort as he understood that a few soldiers had been sent from Caesarea to assist him.

He had to find somewhere peaceful where he could be alone. There was an olive grove nearby; he would find some shade there, sit and think further on his invention. In the event, nothing came to him, but it was, nevertheless, very pleasant. For the first time in months he was not responsible for anything, and he intended to enjoy not doing anything, and taking a long time not doing it.

He was about to return to camp when he saw a man and a woman walking towards him, and from the way they had altered course after seeing him, and the woman had pointed at him, they were obviously looking for him. As he got up and they got closer, he recognized the woman: Rebecca, the Christian woman he had saved from being stoned for blasphemy by some Jewish fundamentalists.

"Greetings to you," he said, as they approached.

"Greetings," Rebecca replied. " Legatus , this is James, the brother of Jesus, and James, this is Legatus Claudius Scaevola."

"As it happens, I am no longer a Legatus ," Gaius replied with a smile, "so I am afraid if you want something, I may not be able to help."

"I gather you were responsible for the extraordinarily large amount of money that was thrust upon us yesterday," James said. "We wish to thank you."

"You will thank me best by using it only for the benefit of the poor," Gaius replied.

"It will all be so used," James replied. "Why did you do that?"

"I chose you to distribute it because I thought you would be the most trustworthy for that purpose."

"What I meant was, why give it to the poor through Christians?"

"You think it was atonement for Romans crucifying your brother?" Gaius asked curiously.

"Was it?"

"Sorry if I disappoint you, but no, it wasn't."

"Good! I would only be disappointed if it were. But you haven't answered. Why?"

"Then this will probably disappoint you. I honestly don't have a good reason. I came across a group of Jewish thieves who were trying extortion on a caravan and a group of Roman auxiliaries who were probably also demanding money from the caravan for protection. I was really annoyed, but I didn't know what to do. Then that solution just came to me. It was the one solution in which nobody in the wrong could benefit, and the ones who did benefit were those who were completely innocent, at least on this matter, and who really needed help. I trust you to give it."

"And you didn't try to benefit yourself." This was a statement, not a question.

"Why would I?" Gaius said in a puzzled tone.

"That you ask that question is its own answer."

"You're going to try to convert me," Gaius smiled.

"No, I'm not," James shook his head. "There is no need to convert you, as you put it."

"You can't be both a priest and a Legatus ," Rebecca added.

"My brother was a great teacher," James continued, "and he always insisted it's what you do that counts. The solution, as you put it, may have come to you, but it came from somewhere."

"And you know from where." This was also a statement.

"Where you think it came from is irrelevant," James shrugged. "What is important is that you listened."

"You must keep listening," Rebecca added. "There will be many more times. ."