"What?" Zircon looked up sharply. "How did he arrive at that conclusion?"
"From Dr. Williams' sketch."
"Hmmm." The big scientist checked the detonator thoughtfully. "He must have figured on a straight upward flow of the magma. But from the shape of the magma front, I think it's highly unlikely that it will progress in any such regular fashion. Instead, the front probably will increase erratically, but in a kind of progression. It may double its frontage at approximately regular periods."
Scotty scratched his chin. "Double its frontage, huh? What does that mean?"
"Maybe four hundred square feet today, eight hundred tomorrow, and sixteen hundred the day after. We won't know the rate of growth, or the time scale, until we've watched it for a while. But I talked with Balgos and Hartson last night at some length, and their opinion is that we probably have a couple of weeks, maybe even three or four. But not months."
Rick whistled. "That fast? When will we be sure?"
Zircon shrugged. "Can't tell. We'll keep shooting on a daily schedule, and perhaps in three or four days we'll see enough growth in the front to make an estimate. But even that can be misleading. If the magma strikes a softer area, it can grow even more rapidly. Our best bet will be to keep a daily watch from now on."
Rick looked up at the extinct cone of El Viejo. In his imagination he saw the top blow off in an earth-shaking explosion and millions of tons of white-hot lava spurt high in the air. Then, when the lava came down ...
"We'd better get on the ball," he said. "Almost time for our first shot."
"Want to connect up?" Zircon asked.