The lower course having been built up in this manner to a height of six inches wooden arches were placed at intervals the lengths of the corridors which were now ceiled over by the simple expedient of fastening thin wooden strips lengthways of the corridors from arch to arch until the corridors were entirely roofed. The strips, or boards, which overlapped one another, were fastened in place by wooden dowels driven through them into the peripheries of the arches. As this work was progressing the walls of the various chambers and the outer wall of the building were raised to a height of twenty-four inches, bringing them to the level of the ceilings of the arched corridors, and the spaces between chambers and corridors were packed with bowlders, the interstices between which were filled with smaller stones and gravel. The ceiling beams were then placed across the other chambers, timbers six inches square hewn from a hard, tough wood being used, and in the larger chambers these were further supported, at intervals, by columns of the same dimensions and material. The ceiling beams being in place they were covered over with tight fitting boards, doweled to place. The ceilings of the chambers now projected six inches above the surrounding course of the structure, and at this juncture hundreds of cauldrons were brought in which a crude asphaltum was heated until it became liquid and the interstices of the next six inch course were filled with it, bringing the entire completed course to the same level at a height of thirty inches, over all of which a second six inch course of rock and asphaltum was laid, and the second story laid out and completed in a similar manner. The palace of Adendrohahkis, constructed in this way, was two hundred twenty feet in diameter, and one hundred ten feet high, with thirty-six floors capable of housing eighty thousand people, a veritable ant-hill of humanity. The city consisted of ten similar domes, though each slightly smaller than the king's, housing a total of five hundred thousand people, two-thirds of whom were slaves; these being for the most part the artisans and body servants of the ruling class. Another half million slaves, the unskilled laborers of the city, dwelt in the subterranean chambers of the quarries from which the building material was obtained. The passageways and chambers of these mines were carefully shored and timbered as the work progressed, resulting in fairly commodious and comfortable quarters for the slaves upon the upper levels at least, and as the city was built upon the surface of an ancient ground moraine, on account of the accessibility of building material, the drainage was perfect, the slaves suffering no inconvenience because of their underground quarters.