no one but himself. We all know that Zoanthrohago is his brain and Gefasto his sword."

"However," warned the other, "be careful of Zuanthrol," and he departed.

Kalfastoban Vental set the new slave to work upon the timbering of the tunnel as it was ex­cavated from the great moraine that formed the quarry, the line of slaves coming from the surface empty handed passed down one side of the tunnel to the end, loosened each a rock, or if heavy a rock to two men, and turned back up the tunnel’s opposite side, carrying their burdens back to the spiral runway used by those leaving the workings and so up and out to the new dome. The earth, a light clay, that filled the interstices between the rocks in the moraine was tamped into the opening behind the wall timbers, the tunnel being purpose­ly made sufficiently large to permit of this. Cer­tain slaves were detailed for this work, others carried timbers cut to the right dimensions down to the timbering crew, of which Tarzan was one. It was only necessary for this crew of three to scoop a narrow, shallow trench in which to place the foot of each wall board, set them in place and slip the ceiling board on top of them. At each end of the ceiling boards was a cleat, pre­viously attached at the surface, which kept the wall boards from falling in after being set in place. The dirt tamped behind them fastened them solidly in their places, the whole making