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exacting studies that you will undertake in all your sub-sea careers. As a small part of it, you will take part in investigation of the rock around us, five miles under the surface of the sea, two miles deep into solid rock.
    “Gentlemen, I can hardly exaggerate the importance of what you are going to do here.”
    He paused for a second.
    Then he said:
    “You are here for one reason only. You are going to learn the science of forecasting subsea quakes.”
    What a two week period!
    The first days in the Academy were rough and rugged, but nothing like this. Without a break—almost without time to catch our breaths—we were plunged into long, sweating hours in that dismal dungeon under the rock sea floor. Study and practice and more study, with the lash of Lieutenant Tsuya’s sardonic tongue stinging us on. He was a good man, that Lieutenant Tsuya; but his orders were to pump us full of the lore of sub-sea seismology in two short weeks.
    He was determined to do it if it killed us. As a matter of fact, it felt as if he came pretty close!
    First was theory:
    Long hours of lecture, study, examination. What is the earth’s crust? Rock. Is rock solid?
    No—not under pressure! For under pressure even rock flows. Does it flow evenly? No! It sticks and slips, and pressures build up.
    “Quakes happen,” droned the lieutenant, “because the rock is not completely plastic. Stresses accumulate. They grow. They build up—and then, bang. They are released.
    “Quakes are simply the vibrations that dissipate the energy of these suddenly released stresses.”
    We had to learn all sorts of strange new words, the language of seaquakes. I remember Bob mumbling, “Epicenter, epicenter—if they mean the center of a quake, why don’t they say it?”
    And Harley Danthorpe: “Lubber! The epicenter is the point on the surface of the earth just above the center! Why, the center may be twenty miles down.”
    We had to learn the three chief types of seismic wave: The thrusting, hammering primary “P” wave—the first to reach instruments, because it is the fastest, racing through the substrata of the earth at five miles a second. The secondary “S” wave—three miles a second, vibrating at right angles to the direction of its travel, like the shaking of a clothesline or the cracking of a whip.
    And then the big one—the slow, powerful long or “L” wave, the one that does the damage. We learned how by measuring the lapse betwen “P” and “S” waves, we could forecast when the destructive “L” wave would arrive.
    And we learned a lot more than that.
    For one thing, I learned something about our teacher, Lieutenant Tsuya.
    We plotted our first maps—like the map Lieutenant Tsuya had projected on the wall for us, showing the stresses and faults in the earth’s crust for hundreds of miles around, with shading to indicate thermal energy and convection flows (for, remember, even the rock flows that far down!), with lines that showed microseisms, trigger forces, the whole lore of the moving rock.
    Lieutenant Tsuya criticized them, and then he relaxed.
    We sat there, all of us, taking a rare break, while the beads of salt dew formed on the pressure-concrete walls and drops of sweat plinked from the ceiling.
    Bob Eskow said, “Lieutenant. The yeoman told us we couldn’t have edenite down here because the geosonde couldn’t get through. Was that right?”
    Lieutenant Tsuya’s almond face smiled. “No. It is a matter of forecasting.”
    He stood up and touched our maps. “All this information,” he said softly, “comes to us through instruments. Very delicate instruments. That is why the station was located so far beneath the city. Any vibration, from traffic or the pumps, would disturb them. You must learn to walk softly here. And you must avoid dropping heavy objects.”
    “Yes, sir,” Harley Danthorpe spoke up promptly. He nodded alertly, watching the lieutenant with his calculating squint, as if he were looking for the