The Seven Hills by John Maddox Roberts

when it came to display.
    Thought of Rome darkened his mood. He knew that he had many enemies there. His family protected him, but to some his actions of late smacked of treason. If only he could make them understand that he held the key to Rome's fu ture greatness! Romans were for the most part conservatives and traditionalists. The scions of the great old families like his own wanted only to reestablish Rome as it had been in the time of their ancestors. He knew this to be folly. The world was very different than it had been in the day of Fabius Cunctator.
    Besides, he thought, their vaunted traditions and system hadn't done them much good when it came to dealing with Hannibal, had it? This new world would call for new methods and new ideas, as much as that might pain the ancestor worshippers of the Senate.
    He went into a huge courtyard where men were erecting, employing or tearing down structures of wood and metal.
    Some were catapults, some scaling devices and some objects of no function he could guess at. Once in a while a timber or rope would break under too much stress and there were shouts or laughter or the screams of injured men. Never before had Marcus seen men so frantically employed, yet seeming exhilarated at the task, strenuous, frustrating and dangerous though it might be. These "active philosophers," as someone had dubbed them, were a new breed of men.
    He went to an especially strange structure that consisted of a platform between uprights, the platform suspended by a complicated armature of ropes, pulleys, gears and what ap peared to be large boxes full of metal bars. "What might this be?" he asked the sweating supervisor.
    "We aren't sure yet what to call it," said Chilo. He was the head of the Archimedean school, but he was as dusty and ill kempt as the slaves who assisted with the work. "The new falling-weight catapults got us thinking about the possibilities of falling weights. It seems such a simple thing, something we all tend to take for granted, yet there is a whole unknown field of study here: the dynamics of falling weights."
    " 'Dynamics'?" Marcus said.
    "It's an old word we've revived. It means the study of how matter moves. Remember when you first came here and I told you that we seek out fundamental principles? Well, this is one of them. Matter does not move about, at random and free from obedience to natural law. There are rules, and we intend to discover them. Watch this."
    At Chilo's direction, a dozen slaves crowded onto the platform. A single slave seized a rope and began to haul back on it. There was a clacking of gear wheels and the platform began to rise, a few inches with each pull. At the same time, the boxes of metal bars descended at the same rate.
    "You see?" Chilo said. "The strength of a single man is sufficient to raise many men. This can be used to raise soldiers above an enemy rampart, but more important to us is the demonstration of the properties of the counterweight."
    He looked around and indicated a man who sat on the edge of a fountain, staring at the machine. "You see that sour- faced fellow observing over there?"
    Marcus looked at him. "Isn't that the mathematician who just arrived from Crete? Nikolaus, is it?"
    "The very one. He seeks to penetrate to the very essence of this question: the principle of why objects fall as they do."
    "Why?" Marcus said. "Self-evident, isn't it? Things have always fallen."
    "That's just it. It isn't self-evident at all. We just take it for granted. Why doesn't smoke fall? What holds clouds up? They may not have much mass, but they have some. Some of us think that Archimedes' principle of buoyancy is involved, but Nikolaus thinks that there is a fundamental, universal force involved and he wants to understand it."
    "Too deep for me," Marcus admitted. "But I like this machine. It could have all sorts of uses. Can you make one high enough to take people all the way to the top of the lighthouse?" The lighthouse of Pharos, tallest structure