Portable Wireless Telegraph Stations WIRELESS TELEGRAPHY is being widely used at the present moment in the Russian-Japanese conflict. In order to show the convenience of this means of communication in time of war, it will be sufficient to state that a safe connection up to more than four days' marching is possible when working with the Morse apparatus, while in the case of acoustical records a distance even twice as great may be covered. We illustrate herewith the portable wireless telegraphy stations designed by the Gesellschaft für Drahtlose Telegraphie, of Berlin, Germany. The stations are arranged for 2-wave lengths, namely for a short wave of 350 meters (1,148 feet), and a long wave of 1,050 meters (3,444.8 feet), the antenna remaining the same, for both. In the case of the short wave, the latter will oscillate in 34, and with the long wave in 14, of a wave. The antenna is outbal anced in the first case by a counterweight consisting of about 6 square meters (64.7 sq. ft.) of copper gauze stretched out at a height of about 39/2 inches from the ground; while the amount necessary in the second case is as high as 24 square meters (258.3 sq. ft.). The antenna is supported either by kite balloons or by linen kites. Each station comprises three twowheel carts-namely, the power cart, the apparatus cart, and the utensil cart. The power cart contains the source of current, that is, a 4 horse-power benzine motor direct-coupled to an alternating-current generator having an effective output of about 1 kilowatt, and to the exciting machine. In a special reservoir is carried the benzine necessary for about 30 hours' continuous telegraphic service. The balloon is pulled in by means of a conical friction clutch, causing a cable drum on the outside of the protective casing to rotate. The apparatus cart, separated into two compartments, contains both the sending and receiving apparatus; while the utensil cart contains the gas reservoir and the necessary intrenching tools, as well as the balloon and a reserve benzine reservoir. STEEL WATER TANK REPLACING STANDPIPE AT COLLEGE HILL, A SUBURB OF CINCINNATI, OHIO. The same outfit has been used in connection with the Gordon-Bennett Cup Steel Tanks vs. Standpipes STEEL TANKS elevated high on posts are rapidly taking the place of standpipes in cities where natural elevations are not available. To obtain satisfactory pressure, water must be stored above an elevation of 100 fet. Thus, in a standpipe located on level ground much of the water contained therein is useless in affording pressure. The advantage of the elevated tank over the standpipe is that, for the same cost of construction, from two to three times as much water can be Istored at the desired elevation. One of these tanks recently built at College Hill, near Cincinnati, Ohio, is shown herewith. It is 154 feet high, and holds 100,000 gallons of water. This tank stands on top of four steel posts, and is reached by lofty stairs winding about the water-pipe. At the top of the stairs is a space around the tank, banistered off for an observatory. The tank not only has proved very serviceable to the suburb, but is an ornament to the land on which it stands. At Galion, Ohio, the old standpipe proved so unsatisfactory that the city council required the Water Company to increase its storage capacity by building a tank. This has been erected, and now the pipe leading to the bottom of the tank as its central support is the old Galion standpipe. The Water Company claims that a saving of $1,500 per year in operating expenses has been achieved The tanks are made with hemispherical bottoms, which design is said to be ideal. Steel tanks are also gradually supplanting the wooden structures used by railroads. It is not necessary to keep them full in order to prevent shrinkage or collapse; and a portion of the bottom may be used as a receptacle for sediment, which can be drawn off without emptying the tank or interrupting its use. Grain-Bucket Tram ways race for signaling the progress of the AWAY out at the town of Wawawai, race from one point of the course to another.-A. G. on the Snake river, in Whitman County, Washington, is a "bucket tram way" that is used in conveying grain from a lofty bluff down to the steamboat landing. Bucket tramways out West are not infrequently used for conveying ores in connection with mining operations; but this, so far as known, is the only "grainbucket tramway" in use in the world. At the top of the bluff stands one immense grain warehouse. At the foot of the bluff on the river's bank, stands another. The elevation of the upper warehouse is 1,700 feet above the stream, and the distance between the two warehouses is 5,150 feet. The endless cable of steel wire is thus nearly two miles long. The upper terminal of this cable tramway is a cast-iron wheel eight feet in diameter, furnished with a patent ratchet grip through which the cable passes, and a smooth, band-iron grip brake for regulating the speed. The lower terminal is constructed in the same manner. The grain delivered at the upper warehouse is placed on "carriers" and sent down by cable to the lower terminal. The tramway is operated by gravity, the loaded carriers drawing up the empty ones. The receiving cable terminal is placed. in the tower of the lower warehouse; and the grain is conveyed in chutes from this tower, either to separate sections of the warehouse, or to the steamers in waiting. This tramway has a capacity of handling 200 tons of grain per day of ten hours, or a total of 75,000 sacks during the wheat season. The "carriers" or frames are placed along the cable at intervals of eighty feet. There are 128 of them, so that 64 are constantly de GRAIN-BUCKET TRAMWAY IN OPERATION. scending loaded, and 64 ascending empty. A man sits at the upper terminal, and by means of a lever operates the brake that regulates the speed. This tramway has proved very successful. It saves a haul of from 15 to 25 miles over a rough, rolling country, down to the nearest railroad station.-J. M. B. Better Railway Sanitation. D ANGERS of railway sleeping cars and plush seats in day coaches have been the objects of special condemnation by the State of Kentucky, which thereby has won the approval of every railway traveler in America. The Kentucky State Board of Health places the plush seat under state ban, declaring it to be one of the most dangerous receptacles of filth and disease germs. Either leather or cane is permitted as a substitute. Linen would also make a good seat covering in that it could be taken off and cleaned at frequent intervals. CHALK by CARL S. DOW. Number Ten-The Condenser T The Steam Engine HE piston in the cylinder of a steam engine is compelled to move back and forth by the expansive force of the steam, which is admitted alternately to either end of the cylinder. As the steam is under great pressure (from 80 to 200 pounds per square inch), the force acting on the piston at a given instant is enormous. After the steam has forced the piston to the end of the cylinder, a valve opens and allows the steam to escape. This steam is called "exhaust steam" because it is at low pressure and much of its energy has been exhausted. Pressures Let us understand at the outset that the force causing the piston to move is net pressure, or the difference between the pressures on the two sides. In other words, if steam at 100 pounds per square inch is pushing the piston, and a pressure of 15 pounds per square inch is on the other side, the force tending to move the piston is 100 15 (85) pounds per square inch. The result would be the same if 85 pounds were the intensity of pressure on one side and zero on the other. sure. This back pressure is sometimes called the "exhaust pressure." Steam Engine Without Condenser The first sketch on the blackboard (Fig. 1) illustrates the cylinder of an engine, showing the piston, etc. The numerous small arrows indicate the highpressure, or entering, steam; and the few arrows on the other side of the piston represent the low-pressure, or exhaust, steam. After having done the work of pushing the piston through a stroke, the steam is driven out of the cylinder by the piston on the return stroke, and thus forced into the atmosphere. Since the steam exhausts into the atmosphere, the back pressure must be greater than atmospheric; if this were not so, the steam would not be forced into the air. In actual practice, the back pressure is about 2 pounds greater than atmospheric. It is a well-known fact that the atmosphere exerts a pressure of 14.7 pounds per square inch; this is usually considered as being 15 pounds. Steam Engine With Condenser Steam is a vapor of water. A cubic foot of water will make about 1,700 cubic feet of steam at atmospheric pressure. From this we can see that when steam is condensed, its volume is decreased. With a decrease in volume comes a decrease (Rights of Publication Reserved by Author) This shows that the power of an engine can be increased by increasing the steam pressure or by decreasing the back pres (488) in pressure. Hence by condensing the exhaust steam, the pressure is reduced until it is almost nothing. In fact it is In fact it is often reduced 12 to 13 pounds. To thus reduce the pressure, the exhaust steam is conducted to a condenser; that is, the cylinder is placed in communication with a vessel cooled by water which enters in the form of spray (see Fig. 2). This cooling draws the exhaust steam from the cylinder, and, by condensing it, reduces the resistance, as already stated. Gain by Condensing Let us determine, if we can, the gain in power due to condensing the exhaust. Suppose the indicator card from a noncondensing engine is represented by the diagram (Fig. 3) on the blackboard. It is evident from the foregoing, that the entire card is above the atmospheric line. The scale of pressures is laid off as shown. In a previous Chalk Talk, we learned that the area of an indicator card is proportional to the power developed, and also that this area is equal to its length multiplied by a height representing the mean effective pressure. Therefore, the work done may be represented by the rectangle A B C D of Fig. 4. Although steam is admitted at 100 pounds per square inch, the average net pressure in this case is only 70 pounds. Now let the exhaust steam enter the condenser. The back pressure will now be about 12 pounds below atmospheric pressure (see Fig. 5). The actual reduction in back pressure will then be 14 pounds; and the power developed will be represented by the rectangle B C E F, if FE is drawn below the atmospheric line to the same scale as BC is above. Now, if the power developed while non-condensing is represented by the expression, 70 X Length of Card, and that developed while condensing is 84 X Length of Card, then the increase is evidently 14 X Length of Card, and the gain per cent is 14 x Length of Card-=20% The gain in power does not indicate the gain in economy, although it is often economical to use a condenser. The relative cost of the fuel and cooling water is the important factor. |