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Cement as a substitute for iron is being tried with considerable success in the building world. For years it had been thought that nothing but iron could be used in the construction of buildings, but it remained for a Chicago architect to devise a cement which, it is claimed, will, in many instances at least, make an excellent substitute for iron. This cement is made like ordinary cement, but does not have for its ingredients the same amount of sand, water and cement as that used in preparing mortar for the building of sidewalks. When a beam has been made of cement it is tested by being subjected to a weight placed anywhere between the supports upon which the beam rests. In one of the big buildings recently erected at the University of Chicago, 60,000 square feet of cement flooring takes the place of the same number of feet of iron girders, and there are a number of 25-foot spans which have successfully stood all tests to which they have been subjected. COMPRESSED AIR—WHAT IT MEANS TO THE WORLD In this latter day, when every known method of time and labor saving is being tested and rapidly put into use, the value of compressed air has become so apparent that every large city, and many smaller places, are making some use of this power. Some of the larger cities use it as a means of transmission of mail, packages, etc., about the city, from place to place. This type of pneumatic tube is the most advanced and it is only of recent development. The most common use to which compressed air is put for carrying purposes is that in pneumatic tubes in the great stores, hotels and newspaper offices. By means of brass tubes leading from a central station to every section of a store, or to the numerous rooms of a hotel, power is conveyed. At the central station there is a pump which develops an air pressure of about 2 pounds to the square inch of pipe surface. For long distances and for great speed, where much use is made of the system, greater power is necessary. In each station where the tube is used there is a receiving and sending apparatus. Two pipes complete the circuit, one with air traveling away from the central station and the other with it rushing toward the home plant. The sending device differs according to the necessities of the occasion. Many plants which do not need heavy pressure simply have an opening in the tube covered by a lid. When it is desired to send something, a small leather or metal box, conical in shape, and with furry ends to make it fit closely to the tube, is opened, and the article is enclosed, after which the sending box is closed and dropped into the tube. It takes only a few minutes for this box to travel about a mile. When it reaches its destination it falls into a box which is provided with a door, and is so arranged that the power may be cut off before opening it to take out the carrier. Some receivers simply have a lid held in place by a strong spring, so that when the carrier is forced against it, it gives way and the carrier falls out upon a desk. By means of these pneumatic tubes money for payment of articles is carried in stores from sales clerk to cashier and the change and receipt for the purchases are returned. In hotels, mail is delivered over the entire building, sometimes over 15 floors or more. Newspapers, calling cards, etc., are also sent to guests. In newspaper offices, these tubes play an invaluable part. All the copy for news matter, advertisements, etc., is "spouted" to the composing room with great rapidity, thus saving the bother of a host of messenger boys, as well as doing the work without loss of time. One feature of the newspaper work is the great pneumatic tube service in the large cities, in use by newspaper associations. Such bureaus as the great Associated Press, which sends out tens of thousands of words of news matter daily, could never do so speedily were it not for the great serpentine tubes that wind about below the city pavements connecting its headquarters with every newspaper office which receives its service. By this means the "hottest" news is shot over to the newspapers in time for publication, whereas were messengers used, the delay might be vital. Of late years the United States Post Office Department has been an active user of compressed air. Several cities are now served by pneumatic tubes, and are able to send mail from postal headquarters to branch stations with very little loss of time. Packages weighing several pounds may also be sent. One of the greatest of these systems will shortly be in operation in Chicago. The cost will be many millions of dollars, but the improved service in dispatching mails and in collecting them will amply repay for the outlay. Aside from the use of compressed air in pneumatic tubes, this agent has been found valuable in many other capacities. One of the most common uses to-day is that in cleaning. A hose is attached to a compressed air pump and by means of a nozzle which may be opened or closed at will, a stream of compressed air is directed against upholstered furniture, carpets and many such articles that gather dust readily. The effect is a cleaning operation of marvelous rapidity. In this manner are the coaches of a railway cleaned after every trip. In the large cities it is no uncommon sight to see a van drive up to a large office building. From this vehicle is unreeled a hose attached to a compressed air machine. The hose is pulled up through a window on, perhaps, the twentieth floor, and carpets are cleaned on the floor, and chairs, sofas, etc., are renovated. Compressed air serves many other purposes, where power is needed. By it ladders are raised or lowered, elevators and automobiles are operated and engines are run by this means. SUGAR CANE IN SUGAR MAKING AND PAPER MAKING |