Are you worried by any question in Engineering or the Mechanic Arts? Put the question into writing and mail it to the Consulting Department, TECHNICAL WORLD MAGAZINE. We have made arrangements to have all such questions answered by a staff of consulting engineers and other experts whose services have been specially enlisted for that purpose. If the question asked is of general interest, the answer will be published in the magazine. If of only personal interest, the answer will be sent by mail, provided a stamped and addressed envelope is enclosed with the question. Requests for information as to where desired articles can be purchased, will also be cheerfully answered. To Make Ice Describe a device for making ice in small quantities.-L. M. B. The following is a device by which good results can be obtained. In Fig. 1 is shown a cylindrical case, A, suspended on trunnions in a frame and capable of rotation by the crank handle shown. The cylinder is open at both ends, to which covers are fitted, however, as shown in the figure. In Fig. 2, B represents a nest of cylinders seven in number and secured between heads. No two of these vessels are of the same size, the diameters decreasing from the largest down in regular proportion. This assemblage of cyl inders fits into the case, A, and it is into the cylinders that the water to be congealed is placed. The object is to produce a uniform lining of ice in each cylinder. It follows that the quantity of water introduced in each must be measured with accuracy. This is easily done. by the tray shown in Fig. 2, in which there is a ledge upon which the nest B, rests. The nest is maintained at such an angle that only a certain amount of water can be poured out of the cylinders, which amount is obviously directly proportional to the diameter of each tube. The compartments are next inserted in the case, A, the cover placed on and secured. The case is then reversed and the other cover taken off, so that a mixture of equal weights of nitrate of ammonia and water can be poured in. This fills the interstices of the tubes. After this has been done, the cover is put back and fastened, and the apparatus rotated for five minutes by a crank. This suffices to produce a materially thick film of ice around the interior of each cylinder, and these films. can easily be taken out. It remains only to fit one cylinder of ice into the other and so to continue until all are fitted to gether to produce a solid block of ice. weighing about eleven pounds. Kitchen Boiler Explosion What is the common cause for explosion of 'kitchen boilers?-C. R. G. The direct cause, of course, is a greater pressure in the boiler than it can withstand. Accidents of this sort can easily be avoided by exercising a little intelligence and care. The hot water cock should always be opened the first thing on entering the kitchen every morning. If the water flows freely, fire may then be started in the range without danger. The diagram shows the connections, and when water is turned on from the main supply, the entire system is filled. When it is filled all outlets are closed, and it is evident that no more can run in, although the boiler is in free connection with and is subjected to the full pressure of the source of supply. When a fire is started in the range and the water in the circulating pipes or water back is heated, the water expands, is consequently lighter and flows out through the pipe into the boiler at A, as this connection is placed higher up than the one at B. This starts the circulation, and the water, as it be ated from the boiler, in the direction indicated by the arrows, the water at the top of the boiler always being much hotter than at the bottom. When the hot cock is open, cold water instantly begins to flow into the boiler at D, by reason of the pressure on the city main, and forces hot water out of the boiler at C. Thus it will be seen that hot water cannot be drawn unless the cold water inlet is free, BARROW FOR DRIVING POSTS. and it is equally evident that cold water cannot enter the boiler unless the hot water cock or some other outlet is open. Platform for Driving Posts Can you direct me how to construct a platform for driving posts? A wagon drawn by horses is very unsatisfactory.-B. O. S. What you desire, probably, is a portable staging that is light enough to push. about. Build a platform of the kind indicated in the drawing, and attach a pair of wheels. Old wagon wheels, or wheels made of boards, will suffice. They should be not less than twelve inches in diameter. The dimension of the other parts should be length of platform, three to four feet; width of platform, two and a half to three feet; height, thirty to forty inches. A board nailed across the handles will render it easy for the worker to ascend and descend. Splicing Rubber Belts Is it possible to splice rubber belts?A. R. S. It can be done if proper care is taken. Strip each ply of the ends to be joined for some eighteen inches, overlap two of the corresponding plies and apply cement. Let the work remain thus for from three to four hours. In like manner treatment is given the next plies, and finally the belt is vulcanized in the press. To secure the best results the work should be done by some manufacturer of rubber belting. To Make Liquid Air Describe the apparatus necessary for making liquid air in small quantities.—G. F. B. One of the simplest methods of liquefying air is shown in principle in the figure. After thorough drying, the air to be liquified enters through the pipe, a, and in the compressor, C, is compressed to about 200 atmospheres (1 atmosphere == 14.7 pounds per square inch). R is a water cooler, to remove the heat of compression. The air thus cooled and strongly compressed passes down through the inner tube of the helical coil, H, to a valve below. Through this valve it escapes into the reservoir, G, the expansion producing a considerable fall in temperature. The cold air then passes from the reservoir up through the outside tube of the helical coil, which surrounds the tube down which the air comes, thus cooling the compressed air in the inner tube. This cooled air is allowed to escape in its R it may be drawn off. With a 3-horsepower engine the yield is about a quart of liquid air per hour. To Drill Glass Will you please explain a method for drilling glass?-H. L. B. Take an old three-cornered file, one that is worn out will do, break it off and sharpen to a point like a drill and place in a carpenter's brace. Have the glass fastened on a good solid table so there will be no danger of its breaking. Wet the glass at the point where the hole is to be made with the following solution: Ammonia, 61⁄2 drachms. Ether, 31⁄2 drachms. Turpentine, 1 ounce. Keep the drill wet with the above solution and bore the hole part way from each side of the glass. Another solution is to dissolve a piece gum camphor the size of a walnut in one ounce of turpentine. Still another method is to use a steel drill hardened, but not drawn. Saturate spirits of turpentine with camphor and wet the drill. The drill should be ground with a long point and plenty of clearance. Run the drill rapidly and with a light speed. In this manner glass can be drilled with small holes, up to 3-16th of an inch in diameter, nearly as rapidly as cast steel. G Smoke for Protecting Fruit Is smoke sometimes used to protect fruit from frost?—S. A. T. Yes. Tar makes the best fuel for the purpose, as it creates a dense smudge. The smoke acts as a protecting mantle. Other material, of course, may be burned -old hay or straw, leaves, etc. TO MAKE LIQUID AIR. turn, becoming still colder by its expansion. As the process continues the temperature falls until liquid air begins to collect in the bottom of G, from which Polish for Hard Wood How shall I polish hard wood handles?— T. J. O. The following simple method is said to be excellent: take a piece of waste and dip it first in linseed oil, then in shellac, and apply it with vigorous rub Freezing of Mine Pump What is the best way to keep a mine pump operated by compressed air from freezing?C. L. S. The best method is that which is usually practiced by miners; i. e., the reheating of the compressed air in the mine, close to the pump. The troublesome question of freezing is completely obviated, under ordinary circumstances, and a large gain in efficiency is also secured. Considering the benefits that accrue from this system it may be stated that it is comparatively inexpensive and it is well worth the trouble in advance to avoid the trouble which results from neglect. Home-Made Screw Driver Please tell me how to make a screw driver.T. A. V. Take an old file some eight inches long and grind it smooth on sides and edges HOME-MADE SCREW Driver. to shape of screw driver. The illustration shows how it will look when finished. Repairing Leaky Pipe 2. For wind pressure the effective section of round and octagon chimneys and chimneys of more than eight sides are taken as one-half the actual diametrical section. Thus, if a chimney has a mean diameter of seven feet and a height of 100 feet, the diametrical section would be 7 times 100700 square feet, of which 350 square feet is regarded as the effective I should like to know how to quickly repair surface acted upon by a gale of wind. a leaky pipe.-A. C. R. Secure clamps of the kind shown in the drawing. These can be made so as to take three or four different sizes of pipe. Rubber gaskets and small sheet steel plates must be used in connection. These plates and gaskets must be one inch square and one-eighth inch thick. The plate should be bent to fit the pipe. For square chimneys, the effective section is taken as the actual diametrical section, from which it will be seen that a square chimney presents twice the surface for wind pressure as does an octagon or round chimney, the mean diameter of which is equal to the length of side of square chimney, the height being the same. type of instrument which is installed in buildings to give an alarm when the building takes fire. Each of the U shaped metallic strips are built up of a copper strip, and a zinc strip soldered together. One set of strips is thick, and the other thin. They are of the same length. The zinc strips are placed on the inside as shown by the sketch. A rise in temperature causes the plates to be heated and to expand. Unequal expansion of the two arms of the U, causes a tendency to separate, but as one is fixed, the whole effort is extended to the second arm. The plate B which is smaller, absorbs heat more readily, so that if increase is sudden and of a large amount, as is usual at the beginning of a fire, it expands rapidly and makes contact with A through points C and C. A being of greater bulk, takes longer to heat and expand. If the air becomes heated from ordinary causes, the rise in temperature always being more gradual, the plate A has time to expand, and the two contact points C and C do not touch. These contacts are made of bent silver or platinum strips, so that contact may take place in all positions of the plates. When the strips C C touch, it closes an electric circuit which rings a bell, this bell being located at the point where the alarm of fire is desired. The particular advantage of this type of instrument lies in its automatic action for preventing false alarms. Making an Electroscope Can you suggest how to make a very simple electroscope, entirely for the purpose of experimentation?-M. D. C. Take an ordinary needle, a piece of cork, and a sheet of writing paper. From the paper cut a small arrow. Push the needle into the cork, and balance the arrow on top. Your instrument is ready for work. Next take another piece of paper, heat it over a lamp or stove, and rub vigorously with a bit of woolen HOME-MADE ELECTROSCOPE. cloth or felt. If the paper so treated is brought near the arrow it will turn with the paper, as it is moved back and forth. |
