The rise of British factory-life and great energy in manufacturing began with the invention of the spinning-frame by Arkwright, the power-loom by Cartwright, the spinning-jenny by Hargreaves, and the mule by Crompton--all within a space of twenty years ending 1785. To these must be added the steam-engine by Watt, which made it possible to drive the machinery, and the gin by Eli Whitney, which made it possible to get cotton to spin. Much as iron has loomed up lately, the working of the various fibres--cotton, wool, flax, hemp and jute--constitutes the pet industry of her people, and very elaborate and beautiful are the machines at the Exposition, especially attractive and less commonly known being those for working long or combing wool, flax, hemp and jute. The United States is not doing as much as it ought in the working of these fibres, and the money which is paid for the purchase of foreign linens and fabrics made of other materials than cotton and wool might, some economists think, be employed at home in making them. The day will come probably, but does not seem to be hastening very fast, when we shall conclude to make our own linens, as we have within a comparatively few years past determined in regard to all the staple varieties of carpets. [Illustration: INGRAM'S ROTARY PERFECTING PRINTING-MACHINE.] One of the most important machines in the Exposition, from the American point of view, is the "double Macarthy roller-gin," exhibited by Platt Brothers & Co. of Oldham, England. It is a curious instance of how machines sometimes revert to their original types. The oldest machine for ginning cotton is undoubtedly the roller-gin, and it was known in India, China and Malaysia long before Vasco da Gama turned the Cape of Good Hope and opened the trade of the East to the Portuguese and their successors. The common roller-gin of Southern Asia was shown at the Centennial from Hindostan, Java and China, and is exhibited here from Java. It has a pair of rollers about the size of broomsticks, close together and turning in different directions, which pinch and draw the fibre through, while the seeds are prevented from passing by the closeness of the rollers. Whitney's invention of the saw-gin in 1794 revolutionized the business and changed the whole domestic aspect of our Southern States. In it the fibre is picked from the seed by means of saw-teeth projecting through slits in the side of the chamber in which the seed-cotton is placed. But the roller-gin has again come upon the stage, and with the late improvements is likely to become the gin of the future. When the close of our civil war put an end to the "cotton famine," as it was called, in Europe, and American cotton resumed its place in the market, the export of the East Indian and Egyptian cottons would have been immediately suppressed if they had not possessed the roller-gin in those countries. Ten thousand of the double Macarthy gin