STATIONARY ENGINES.

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this means much time is saved over the ordinary method, withthe additional advantage of being able to manufacture bars upto 60 feet long, for deck beams and keels of iron ships, in onelength without a weld, which can only be effected by having a highspeed of the rolls so as to complete the work before the bar getstoo cold. Reversing gear has been used for the rolls, but it isnot to be recommended for them when running above forty-fiverevolutions per minute, on account of the violent shock in reversingthe motion at a higher speed. To roll the length required for theabove purposes the speed at the Dowlais Iron Works is nearlythree times as great, the ordinary rolls running at 120 revolutionsper minute, and the others for large sections at 110 revolutions,the rolls being of the full size—21 inches in diameter.

COMPOUND REVERSING RAIL MILL ENGINES,

AT HALLSIDE STEEL WORKS, NEAR GLASGOW. {See Plate.)

“ The engines are of the compound direct-acting horizontal type,and have two high- and two low-pressure cylinders, whose diametersare respectively 31 inches and 50 inches, while the length of strokeis 5 feet. They act directly on the rolls, by which arrangementthere is obtained a very high speed in the rolling Operation with acomparatively limited speed in the engines, the latter making fromfifty and sixty revolutions per minute. In each case the high-pressure is placed in rear of the low-pressure cylinder, with whichit is connected by means of an intervening receiver. Laid upona bed of hard and tough blue clay, the foundation of these engines—the total weight of which is some 300 tons—consists of a solidmass of Portland cement concrete, 12 feet or 14 feet in thickness,and weighing between 500 tons and 600 tons. To this foundationis fixed the soleplate, which weighs about 60 tons, and carries thetwo pairs of cylinders, as also the two main frames. The latter,which are of the box form, are, as will be seen in the Plate,arranged so as to form a direct connection between the low-pressurecylinders and the crankshaft, while the pedestals for the crankshaftbearings are cast solid with them. Under each crankshaft bearingthe frame has a strong foot, which is not only bolted down to thesoleplate by two holding-down bolts, but which has in addition on