For some years this fabrication had been making considerable progress. Unsized paper, with the sheets impregnated with dextrin and starch and squeezed in hydraulic presses, will form a material as hard as steel. There are made of it pulleys, rails, and wagon-wheels, much more solid than metal wheels, and far lighter. And it was this lightness and solidity which Robur availed himself of in building his aerial locomotive. Everything--framework, hull, houses, cabins-- were made of straw-paper turned hard as metal by compression, and - what was not to be despised in an apparatus flying at great heights-- incombustible. The different parts of the engines and the screws were made of gelatinized fiber, which combined in sufficient degree flexibility with resistance. This material could be used in every form. It was insoluble in most gases. and liquids, acids or essences, to say nothing of its insulating properties, and it proved most valuable in the electric machinery of the "Albatross."