Free Salamander by David D. Friedman

Magister?”
    He hesitated a moment, opened his tablet, looked down at the first leaf. “It is your decision but I have a few ideas. It could be either research in understanding something that already exists. Or research in creating something new. My advice would be to start with the first, and perhaps go on to the second later. I have a short list of puzzles here; you could choose one of them or find another for yourself.”
    “What sort of puzzles?”
    “We have spoken a little about the stability problem—the tendency of constructions, static spells, to decay over time. One of the problems you did last week involved calculating the rate of loss for a simple static spell, and from that, the time to collapse.”
    The girl nodded, said nothing.
    “I have long been puzzled by the stability of the containment sphere. I did some rough calculations a few years ago and concluded that either it was much stronger when it was built—and I could find no evidence of that in the records—or it should have collapsed years ago. You are better fitted than I to examine it, tease out its structure. So one project would be to redo my work more carefully and precisely, calculate how fast the sphere ought to be losing its fire, and, if you can, determine how fast it is fading, either now or using any old records there may be from which its past strength can be deduced.
    “It is a puzzle that should test your abilities. If it turns out to be too easy for you, there is another sphere of fire, a somewhat brighter one, whose continued brightness may pose a still more difficult problem.”
    She looked puzzled for a moment, then smiled. “You mean the sun. I have wondered about that.”
    “Yes. By Olver’s calculation, it ought to have burned out centuries ago; that’s one of the six puzzles he starts the thesis with.”
    “Does Olver have a solution?”
    “Some day you might go and ask him. When I did, he told me that he wasn’t willing to publish half finished work. Perhaps you would have better luck.”
    Ellen shook her head.
    “The containment sphere will do for the moment. Do you want me to work it all out myself, or am I free to look for information from others more familiar with the construction?”
    Coelus shook his head. “It won’t do you any good. Nobody here knows anything useful and I searched through the library years ago. If Durilil left any description of how the sphere was constructed, it is long lost.
    “But you are welcome to look. This is a project, not a test; there is no need for me to test you any more. In seeking truth, one uses what one can find.”
    * * *
    “You’re sure you want to risk it?”
    Maridon nodded. “You invented the Cascade effect and you are the only one who really understands it. If something goes wrong, you have to be here to fix the schema and try again. I do not.
    "Are all the preparations made?”
    Coelus looked around the lawn. Maridon had taken the center position with three mages arrayed in their appointed places around him. With himself in the fourth position as air, all four elements were there to start the Cascade. It should be easier than the earlier experiments, with the improved geometry and with all four positions held by elemental mages instead of some only by material symbols. Coelus was in reach of the core line of the first stage; his athame, newly sharpened, lay on the table by his right hand, its silver blade gleaming. With luck, if something went wrong … .
    Maridon glanced at him; Coelus nodded. Everything had been rehearsed; this was it. One side of the lawn was the wall of the magister’s wing, windows shuttered against the late autumn chill. The other was the inside surface of the containment sphere; at least if something did go wrong only the college was at risk. His colleagues, having advised him confidently that his absurd pooling schema could never work, would have no business complaining if it turned out to work too well. Idiots.
    “Ready.”
    Maridon