Through this porous formation the water streams down until near the cup-shaped declivity where it comes in contact with an atmosphere chilled by deposits of salines and chemicals, kindred to those used in making artificial ice. The porous character of the stratum permits the rapid passage of air currents and these, reduced to a low temperature, exert their congealing effect on the water. When the water finally comes to rest in one of the cavities made by the ice-cutters, it freezes from the bottom upwards. This is the theory of the scientists. It has not cannot be proved, unless curiosity should lead some one to dig through rock many feet to determine the solution to this interesting puzzle. Nowhere in this district are there mineral or saline deposits of any character, much less of the kind necessary to freeze water as rapidly as it is frozen in "Bend's Cooler." A single glance at the country. which presents ten thousand external proofs of the terrific and incomprehensible heat to which it was subjected during its volcanic formation, dispels all thought of a chemical deposit. On the other hand, perhaps Nature has an altogether different and peculiar way of manufacturing ice not yet unraveled by the genius of man. Who knows? No one has answered the question as yet. $250,000 FOR A CHIMNEY By GEORGE FREDERIC STRATTON F the gigantic chimney recently completed at Great Falls, Montana, could be laid down on the ground it would form a tunnel through which three railroad tracks of standard gauge could be laid, side by side. The heaviest types of Mogul engines, each one coupled to eleven freight cars, could stand on the tracks without projecting from the tunnel ends. Those tracks would occupy the apex end of the chimney. At the base end there could also be laid down a platform on each side of the tracks, seven feet in width. The bricks used in this chimney would make a six-foot sidewalk, over two and a half miles in length. With them, and the concrete used for the foundation, a dozen eight-roomed houses could be built; and the lumber used for the erecting scaffold would be sufficient to finish these houses. Inside the top of that chimney, as it now stands, a circular table could be set up, with seating capacity for one hundred and twenty-five persons, and with ample room in the center for an adequate force of waiters. The stove-pipe, or flue, which leads into this monstrous chimney is not far short of one-half mile in length; and is fully large enough for four of the largest automobiles to be driven abreast through it, with sufficient margin for safety against collision. Here are the figures: The chimney is five hundred and six feet in height, above the foundation; it has an inside diameter of sixty-four feet at the bottom and of fifty feet at the top. The walls run from sixty-six inches, in thickness, at the base to eighteen inches at the apex. foundation is twenty feet deep, the footing being 103 feet across on the outside, and 47 feet across the inside, with walls, The consequently, 28 feet thick. These are record figures. It is the biggest chimney in the world -the nearest in size being one at Glasgow, Scotland, which is 454 feet in height. The two next highest chimneys, in this country, are the Eastman Kodak Company's, 366 feet, and the Oxford Optical Company's, 365 feet. There are but four buildings on earth which exceed this great shaft in height— the Eiffel Tower, 1,000 feet high; the Metropolitan Life Insurance Company's building in New York, 657 feet; the Singer Company's building, also in New York, 612 feet, and the Washington Monument, 555 feet high. This chimney was built by the Alphons Custodis Construction Company of New York for the smelter plant of the Boston and Montana Consolidated Copper and Silver Mining Company. The necessity for its enormous capacity will be understood from the fact that over two million feet of gases are emitted every minute from the smelting operations-a quantity which, if it was illuminating gas, would be more than sufficient to light the entire city of Greater New York, without calling upon electricity for help. This immense shaft is capable, however, of carrying off a much larger amount than this-four million feet per minute being its maximum capacity. It is so designed that sixty feet more in height may be added as the expansion of the smelter requires. It is built upon the summit of a hill, three hundred feet above the level of the valley; and two thousand feet from the smelter with which it is connected by the gigantic, horizontal flue already mentioned. The exposed situation, and the fact that exceedingly severe gales prevail, necessitated the most careful calculation of strains and stresses, and a consequent exceeding strong construction. The plans provided for a resistance to gales up to one hundred and twenty five miles per hour. The foundation is of concrete, and required 5,200 barrels of cement, 2,000 cubic yards of sand, and 4,000 cubic yards of slag. This was built by the company at a cost of $50,000. Before operations were commenced on the chimney this foundation was tested by piling railroad iron upon it up to a total weight of 209,000 pounds per square foot. The chimney itself required 13,000 tons of brick, 3,075 barrels of cement, BRICK PLANT SPECIALLY BUILT TO PROVIDE BRICK FOR THE BIG CHIMNEY. The stack on the hill in the background is the old 200-foot chimney. This photograph was taken before the new chimney was started. 5,225 barrels of lime, 4,180 cubic yards of sand, and 200 tons of acid-proof mortar. The total weight is between 17,000 and 18,000 tons, and the cost was $200,000. In the construction operations 200,000 feet of lumber were used for scaffolding. Four elevators were used, three being operated by electricity and one by steam power. It was completed in two hundred working days which, in itself, is considered a notable achievement. Lightning protection has been well provided. Sixteen rods of one inch, round copper, with platinum points, project five feet above the chimney cap. These are connected to a copper ring surrounding the chimney a few feet below the top, which is in turn connected to two copper cables leading to the ground. A very interesting feature of the construction, and one which goes far towards demonstrating the great preparations necessary for the erection of this chimney, is the brick-making plant. It was built especially for making the hard-burned, radial, perforated blocks with which the chimney is built. The photograph of the brick-yard was taken before the chimney was started, and the chimney seen on the hill is the old, small, 200 foot stack. The brick plant is electrically driven throughout, and contains the most modern machinery, together with nine, down-draft kilns of the latest type. The clay from which the 30,000 tons of brick, for flue and stack, were manufactured, is a hard shale excavated close by and never before worked in that vicinity. It also makes an excellent paver, red front brick, common and hollow brick, as well as a vitrified, tile pipe. On account of the extreme tenderness of the shale after leaving the brick machine, a special method of drying was used. In the lower section of the chimney these bricks had to resist a pressure of twenty-one tons per square foot-but that this was a trifle to them was shown by the laboratory tests, in which their crushing point was found to be 6,000 pounds per square inch, or 400 tons per square foot. The construction of the workmen's scaffold inside the stack was a problem that gave the contracting engineers a great deal of concern. It involved the efficient and safe handling of some 17,000 tons of material, and at the same time the conditions under which the men worked, at great heights, had to be made perfectly safe. It was impossible to use a single floor-beam system on the inside on account of the great diameter of the It was also necessary to design a system that could be raised in the least possible time, when the bricklayers were not working, for those men could not work under the men who were raising the scaffold, on account of the danger of falling material. It was necessary to provide a sufficient number of elevators, of ample size to quickly handle some 200 tons per day. The scaffold consisted of a 12 post tower, made of 10x10 timbers. At each of the four flue openings these uprights were spaced at the proper distance to take a 6x9 elevator. Oak ways were spiked to the 10x10's as guides for the elevator. The cat-head, or cross timbers, at the top of the posts that held the sheaves through which the elevator cables operated, were built of 3x10 timbers, and were held in place on top of the 10x10's by means of a three-fourths inch dowel pin. This was necessary, as the cat-head had to be removed at each raise of the scaffold. Spanning the floor beams were 6x6 timbers on which 2x10 plank formed the floor of the scaffold. When the scaffold was raised the 6x6 and the 2x10 planks were carried up, leaving behind the heavy 8x10 floor beams. The scaffold was absolutely uniform and symmetrical from top to bottom, each seventeen feet being a duplicate of the seventeen feet below. The post load was about eighteen tons, and during the whole construction of the chimney no settlement or buckling was observed. The chimney was plumbed entirely from the outside by a five-foot plumb rule cut to the batter of the chimney and equipped with two level glasses set in planes at right angles to each other. During the progress of the work the center was checked by engineers' instruments, and at the finish by the use of a thirty-pound plumb bob. It was difficult to detect that the chimney was out of plumb, even so much as one inch in the total five hundred and six feet. As a means of communication between the men on the scaffold and those working below, a complete system of speaking tubes was kept in operation at each elevator. One double-drum electric hoist, one single-drum electric hoist, and a 35 H. P. steam engine operated the elevators. The electric power gave a speed of three hundred feet per minute; the steam, six hundred feet per minute. The engine's signals were given by means of an electric bell system, controlled by a pushbutton on top of the scaffold. After the chimney was built the interior was lined with a four-inch sheeting of special, heat-resisting and acidproof bricks, which were made at the same plant, and of the same shale as was used for the regular bricks. |