We began working on the inner wall of the dome with our entrenching tools. That started something! * * * * * It was now clear that if we ever got out of wherever we were, we would have to do it on our own. First, to establish the exact circumference of the dome, I formed all hands, sailors, marines and Japanese, in a single column and we did the circle. I wanted everybody whose lot was our lot, to know every detail that might later prove valuable. The area under our feet, available to us within the dome, we estimated at ten acres. That gave us considerable inner surface of wall and dome to be studied. We could not see the dome, we only knew it was there. We had small radar and sonar sets, but the dome registered on neither. Nothing we shouted was echoed back to us, nor did the chattering of the fast-firers cause reverberations. With those fast-firers, the ultimate in small arms, we searched out every quadrant of the dome, to see if there were any opening. In the same way we searched out every yard of the wall; there was no way out, at least of any size, for I'd have wagered, so carefully was this job done, that if one bullet fired into dome or wall had fallen outside, some one of us would have spotted it. We used up a lot of steel-jacketed bullets, but we found not a single aperture in the wall or dome. Next we worked on our super-grenades, of which we had a fairly good supply. This was dangerous work; we had to dig trenches from which to heave them. Even the rifle grenades were dangerous because of our limited escape area. The grenades did nothing to the wall; nothing whatever. The flame-throwers accomplished little more. There was danger with these, too, for the flame bathed the wall--we could see it strike and blossom up and down--and backfired so that it was a wonder all who stood behind the machines were not wiped out. And even the flames did not affect the wall. We even, so help me, tried to _talk_ a hole through the wall! Yes, Krane thought of it, Trumpeter Krane. "Maybe we could find the key sound of the dome," he said, "and shatter it with sound. You know, like marching steps shaking down a bridge." Well, we tried, but got nowhere. "Shovels, then," I said. "Entrenching tools! Maybe we can go under." All hands groaned. There is nothing a marine or sailor dislikes more than digging in--even when bullets are flying thick and fast. I think we were all a little mad then. It was bad enough to dig down into sand that poured into a hole faster than one could dig, but to accomplish nothing by doing it was heartbreaking. By day we perspired like hippos, rubbed the skin off our palms, got raw and bleeding where our clothes chafed. Water and food were no problem, for our mysterious source of supply never for a moment ceased or abated.