A two-speed movable sidewalk, of the Blot, Guyenet and De Mocomble type, is to be used for conveying visitors at the Paris Exposition, says Engineering News. It differs from those of Chicago and Berlin in the reduction of the weight of the moving platform by spacing the driving wheels 127.5 feet apart and using electricity as a motive power. The driving wheels are mounted in the bed of the track and impart motion to a central rail on the under side of the platform. Bearing wheels, spaced about 20 feet apart under this rail, also carry the platform, and the central rail supports one-half the total weight of the platform; small side wheels carry the other half on side tracks. This arrangement enables the platform, which is divided into sections and hinged, to pass around quite sharp curves. The high speed platform, 4 feet 3 inches wide, is supposed to move at the rate of 6½ miles per hour on a 35½-inch gage track; the slow platform is 31½ inches wide, moves at half speed and runs on a 17¾-inch gage track. The whole structure will be elevated on girders carried by cast iron columns, with stations about 656 feet apart. The high speed platform weighs 146 pounds per lineal foot; and with passengers, nearly 400 pounds per foot. The slow speed platform weighs about half this. The track will be about 2½ miles long; the initial motive power is figured at 472 H. P. and the carrying capacity at 38,880 per hour. The "schlamm," or mud, thrown down from the water of coal washing has hitherto been regarded as worthless, says The Engineering and Mining Journal, except that sometimes a portion of the coal particles it contained have been separated and made of value by a washing process; but Bergassessor Haarmann, of Friedrichsthal, has invented a new method for treating it dry and dividing it into two products, one of which, with low ash content, is distinguished by its granular nature, while the other contains a large proportion of ash and is of the fineness of flour. The former of these two products is, on account of its low ash content, useful for various purposes, and the latter constitutes a fuel quite ready for use in coal dust firing. The method is founded on the circumstances, hitherto lost sight of, that the incombustible constituents of the "schlamm" chiefly consist of clay which was formerly more or less dissolved in the wash water; and on the mud being dried and subjected to a suitable mechanical process, the clay falls into fine dust, while the coal particles, on the contrary, retain their granular nature. The method is carried out by drying the mud and a subsequent fine sifting, which effects a breaking up of the lumps that occur in the dried "schlamm," and a separation into the two products above named. The dust that falls through the sieve has a high ash content, being in the nature of flour, while what remains behind is granular and has a low ash content. It seems to us that this game is hardly worth the candle. ELECTRICAL NOTES.