We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
80 The Audio-Visual Handbook
equipment should be kept as clean as possible. Dust should be removed from the metal parts and from the leather bellows by using an ordinary dustcloth, and should be removed from the lenses by using a lens cleaning tissue or a lintless linen. A very satisfactory type of lens cleaner for these larger lenses is the soft tissue which is used for various purposes in the home. It is not desirable to wash the lenses unless they become rather thoroughly coated with dust or oil, and in that case a soft cloth moistened with benzine will clean the surface quickly.
Although the best projectors can be adapted to almost any situation and will operate with reasonably satisfactory results even in a lighted room, it is usually advisable to arrange a projection table or some other convenient support for the projector and to darken the room. Any manual training department can make a projection stand at very little cost, and can build into it a small drawer to be used for a dustcloth, lens cleaning tissues, an extra lamp, extension cord, and such other items as will be necessary in operating the projector regularly. If light is needed in order that students in a classroom can take notes while slides are being shown and discussed, it is advisable to pull down all the shades, to shut out the interfering daylight, and turn on the incandescent lamps in the room. The incandescent lamps of usual strength will not interfere with the projected picture nearly as much as light from one or two uncovered windows on a clear day. The most satisfactory plan for providing a working light in the classroom is to suspend reflector lamps below the eye level of pupils. One such lamp will provide adequate light for two to four pupils, and several lighted lamps in the room will not interfere with projection.
Adjustment of the Projector. The principal adjustment needed in operating the glass-slide projector is that which will adapt it to the projection distance in a given situation. This can be accomplished quite easily and should give no one difficulty. Other adjustments may be necessary at times to accommodate a sloping desk on which the projector is placed, or to take care of the elevation of the picture to the screen. This can be accomplished usually by loosening the small set-screw at the base of the projector, adjusting the projector, and tightening the screw again.
Sometimes it is necessary to adjust the lamp itself. The majority of the projectors have made provision for this. The lamp socket is mounted in a sliding support which is held in place by a small setscrew at the bottom of the lamp house. After the set-screw has been loosened, the entire lamp assembly may be moved forward or back