Of particular interest was the new kind of cloth, which was much fighter than wool or cotton, and, at the same time, cooler in summer and warmer in winter. This material was made from cork, which was first pulverized and then afterwards digested by means of chemicals. Under hydraulic pressure, a somewhat thick thread was obtained, which had all the good properties of cork, but none of its poor ones. This cork thread, when woven into cloth, made a texture both light and durable, had a velvety touch to the fingers, and being a poor heat conductor, protected the wearer from heat in the summer and cold in the winter. A number of combinations were made whereby cork thread and silk thread were spun together, giving an entirely new product, with all the virtues of silk as well as those of cork. FOOTNOTES: [Footnote 6: When this was written gold coins were legal tender. Gold payments were outlawed by Congress in 1933.] 8 THE MENACE OF THE INVISIBLE CLOAK Leaving the Pennsylvania mills the aeroflyer, traveling at high speed landed the party within a very short time on one of the tall landing buildings in New York. Ralph and Alice made their way down to the elevated roadway, where, at Ralph's suggestion they put on their _power skates_, for, as he explained smilingly, it was but a short distance to his home and the exercise would do them both good and give them an appetite for luncheon. When they were but a little way from their destination Ralph became conscious of a faint hissing sound close behind them. Twice he glanced over his shoulder, but the roadway at that hour--it was just before noon--was deserted. Yet the sibilant sound persisted, seeming to be getting closer and closer, like some persevering insect about to alight. Alice apparently heard nothing, or perhaps she thought it merely one of the noises of the street, for she chattered on in the gay animated fashion that was one of her charms, oblivious to the fact that the man at her side was so preoccupied that he scarcely replied to her. For Ralph had now satisfied himself that there was nothing anywhere around them which could cause that untiring pursuant hiss. Then from what secret invisible source did it emanate--and why? To the scientist, accustomed to explaining the unexplainable, it was ominous--menacing-- Again he turned to look behind him, along the deserted way, and at that moment he heard a stifled cry from the girl beside him. He whirled to face her, and faced--nothing! He was alone in the empty street! Unbelieving, doubting the evidence of his eyes, he stared about him, too astounded for the moment, by this mystifying and amazing disappearance to think collectively. Above him the sun shone in a clear blue sky, before and behind him stretched the still roadway. Then he was aware of the silence, the deadly quiet. For the hissing had receded into nothingness, and with it, Alice.