Thyriel led me to the vacant space whence the airship had been launched; and there I was shown how powerful magnets made the snow-storm sweep so rapidly downwards and held the irelium dust in position, once it had taken shape. Then the alternate floors were exhibited to me, one emanating heat which melted the new structure into a permanency, and another that reduced the temperature below freezing-point and completed the architectural process by chilling the metal. There were other floors easy of substitution by means of leverage and the application of great force; as one was withdrawn, another was run into its place. One was suited for one chemical process, another for another. A second set were for applying to the walls of the new structure different forms or grades of electricity. A third set could infuse into them various kinds of concreting fluids to make them cohere when the heating and chilling process was likely to fail. This was the great Ooloran that I had come to see, and only the most skilled musician and architect was allowed to sit down at the key-board. In order to show me the part that music took in this swift architecture, I was led round the circle of sub-chapels, that I had seen surrounding the great dome. In these were employed the various draughtsmen of Oolorefa. In the first we entered the experimenter was engaged in seeking the most beautiful form for a new mansion which was to be placed up amongst the snows of Lilaroma; it would have to withstand great gusts of wind and at times heavy drifts of snow; it would also have to bear a variety of high temperatures within in order to protect the dwellers from the bitterness of the night. The building was meant for those who had to watch the storm-cone and keep it in perfect working order. The draughtsman was using a miniature Ooloran, and deftly sounding various musical notes, and sometimes songs into its irelium dust whirlwind; but there was always one predominating note, meant to introduce into each experiment a feature that had been before tested and found suitable. He fixed his experiments by means of his small movable floors, and then placed the resulting forms in order along a shelf, attaching to each the score of music which had produced it. It was like a collection of toy observatories. Within a neighbouring compartment of like transparent walls another artisan submitted each of the models to the influences of stress and strain, of heat and cold, of snow pressure and tornado violence that the ultimate and full-sized mansion would have to undergo. One succumbed to the heat, another to the severe cold, a third to an avalanche from above, a fourth to a gust of wind. He marked the flaw in each and the influence that had brought it out, and handed the model back to the draughtsman, who at once corrected the note or notes in the score of music which symbolised the flaw. When the result of the experimentation