International projectionist (Oct 1931-Sept 1933)

30 INTERNATIONAL PROJECTIONIST February 1933 International Photographer Is a finely printed and beautifully illustrated monthly magazine owned by the West Coast Cameramen's Union In all matters concerning the professional motion picture photographers of the country it is the official organ It is designed to appeall to amateur followers of 16mm. cameras as well as to the most advanced technicians The columns of the magazine recognize the close relationship between the photographer and sound recorder If your news or kodak dealer does not carry the magazine on its counters write for a sample copy to INTERNATIONAL PHOTOGRAPHER GEORGE BLAISDELL, Editor 1605 North Cahuenga Avenue, Hollywood, Calif. 25 cents a copy $3 the year Eastern Representative: James J. Finn, 1 West 47th St., New York but one form of energy can be converted to other forms. A good example of the conversion of energy from one form to others is the generation and use of electrical energy. The energy of coal is chemical. When coal is burned the chemical energy is transformed to heat energy, which changes water to steam. The steam confined in a boiler builds up a pressure. This steam under pressure is used to drive turbines mechanically coupled to the generators which convert the mechanical energy to electrical energy for distribution. The electrical energy is converted into various forms as required, such as heat energy to heat flat irons, water heaters, waffle irons, etc.; mechanical energy by electric motors for driving various machines, trains, etc.; light energy for artificial lighting; or into chemical energy for plating metals, charging storage batteries, etc. Since reference will be made to the various forms of energy later on, a brief discussion of the most important forms of energy is entered upon at this point. Forms of Energy (a) Electrical Energy. — ^The generation of electricity by mechanical means is accepted by all of us as a fad. The ease with which electrical energy can be converted into other forms, and the ease with which it can be transmitted from one place to another, has led to its wide use in our modern times. Electricity plays a very important part in the recording and reproduction of sound pictures, and a fundamental knowledge of the behavior of electricity is necessary for a clear understanding of the process involved. Therefore a brief discussion of the principles of electricity will be given later. (6) Light Energy. — Light is anything which affects the sensation of sight. It may seem peculiar to consider light as a form of energy, since it was said that energy was anything which arose from work, or which could be converted into work, or was work itself. It cannot be shown very easily that light is work, but it is easy to see that light may arise as a result of work, as, for example, the red hot sparks that fly from a high-speed saw in cutting steel. In this case a great deal of heat is generated. The heated material emits light, depending on the degree of temperature. Another interesting feature of light is the fact that practically all of the energy which exists on the earth came here as light from the sun. It is this light energy from the sun which produces our winds, and gives us rain and the resultant water power. These effects are commonly attributed to the heat of the sun's rays, but heat does not travel through a vacuum as evidenced by the "Thermos" bottles in everyday use. Practically no heat arrives at the earth directly from the sun, but is produced at the surface of the earth by the effect of the light rays. This gives us a striking example of the transformation of energy from one form to another. When the light from the sun strikes the earth, the surface of the earth is heated, which in turn, heats the surrounding air. Heated air is lighter than cold air and rises, thus setting the air in circulation and producing winds. The warm air evaporates water from the surface of the earth (oceans, lakes, rivers, etc.), and rising warm air currents carry the evaporated moisture up with them until they come in contact with the cooler upper layers of air and are cooled. Cold air cannot hold as much water vapor as warm air so that, when the warm air is cooled, the water vapor contained in it condenses and falls as rain. Some of this rain falls on portions of the earth's surface of high elevation, and the energy of the water due to its elevated position is available for turning water wheels for the generation of electric power. (c) Chemical Energy. — The chemical energy which a substance has is contained in it by virtue of its chemical composition. It is rather difficult to understand what chemical composition has to do with work, but it is easy to understand that chemical energy can be converted into work. Such a conversion takes place in a gasoline, or oil, or steam engine when the chemical energy of its fuel is converted into work fur driving automobiles, motor boats, ships, etc. {To be continued)