Next to their use in removing the waste gases and supplying the necessary draught for do mestic and other heating apparatus, the most important use of chimneys is in connection with steam-power plants and metallurgical fur na•es of manufacturing and smelting works. Chimneys fur power and smelting plants are structures of considerable size and cost. They are built of masonry, usually brickwork, and of metal, usually sheet steel. one of the largest brick chimneys in the world is that of the power plant of the Aletropolitan Street Railway Com pany in New York City, and a description of it will give a very clear idea of the character of such structures as they were built at the end Of the Nineteenth Century. This ehininey is 353 feet high, with an internal diameter of 22 feet : weighs 8540 ton:, and required 3.400,000 bricks for its construction. 1n building the foundations, which cover an area of about 85 feet square, the earth was removed to a depth of 20 feet below the power-house door. and 1300 piles were driven to a depth of about 40 feet over the entire area. These piles were cut off at a level of one foot above the top of the excava tion bottom, and an immense concrete block was laid upon them S5 feet square and 20 feet thick. Smoke-flues lead from the boilers to the chim ney from opposite directions. and as there are three stories in the boiler-house upon which the boilers are installed, there are six large open ings to the chimney, two on each of the three floors, The chimney is built of two concentric shell:. and the outer shell is stiffened by twelve interior longitudinal ribs projecting radially toward the inner shell and having a clearance of inch. The inner shaft has a constant diameter
of 22 feet, and the outside dimensions of the chimney range front a square base 55 feud on a side to a cylindrical neck 26 feet l0 inches in diameter, 316 feet above. The inner shell varies from 24 invites thick at the base to S inches tide!: at the top, and is lined with s inches of fire-brick for a height of 00 feet, and with • inches of fire briek for 25 feet more: above this height the shell is not lined. The outer shell is 2s inches thick 1f inches thick at the top. The top of the chimney is protected by a east-iron cap.
As an example of steel chimneys, that for the Ridgewood pumping station of the Brooklyn. N. Y., water-works may be selected. The height of this chimney from the ground is 217 feet, the minimum diameter is S feet, and the diameter at the base is 25 feet. it is lined with brick for one-half its height. There are 137 plates in the structure, varying in weight from 800 to 1400 pounds, and in thickness from t.i inch to inch. The plates are of open-hearth steel, having a tensile strength of 63.000 pounds per square inch. The chimney was erected in ten weeks, the work of erection being performed from an inside scaffold ing whieh was raised as the work progressed. This •hinmey cost about $10.000. The following taltle gives the location.materiaL height,and diam eter of some of the highest chimneys in the world: