The Educational screen (c1922-c1956])

266 The Educational Screen is one inch by 1 /4 inches and permits twice the amount of light to pass through it during projection. Consequently, the screen image is large and brilliant, especially so when the Bead Screen is used. Another advantage of this double-frame apparatus is that a clear, well-defined image may be projected either on a small screen or on a large auditorium screen twelve feet in height. Knowing that the cost of apparatus and operation is ex Figure 1 Willard D. Morgan This picture shows the Bausch & Lomb double-frame film-slide attachment on the Baloptican projector. This attachment may be turned vertically or horizontally while projecting the filmslides. The lens-mount used jar frojectina the standard 3l4 -f 4-inch tantern-slides may be seen adjacent to the projector. Below are shown a number of film-slide rolls which are used in this projector. A special mat may also be secured in this projector when singleframe film-slides are to be used. tremely reasonable, our next step will be to study the possibilities of obtaining the finest quality film-slides. For those who have never tried developing their own pictures, I may say that there are no mysteries to this fascinating part of the camera worker's art. Good results may be expected from the start, provided the few photographic essentials are observed. A New Film-Slide Development Recently I have worked out a special feature with my Leica projector which gives many new possibilities for the amateur as well as the professional user of film-slides. In modern visual educational practice, there is a growing tendency to show only a fewwell selected pictures during a class period. In many ' cases, where I have visited schools and talked with visual directors, only one or two slides are used during the ])eriod. With such a selective demand on projected pictures, I found that the long strips of filmslides did not fit into the program of these special requirements ; yet there was the immediate demand for projection-slides and apparatus which would be inexpensive, extremely light, portable, and allow for any combination of the slides. Thus a group who were studying about Mexico could use half a dozen slides on the costumes of the people and the next day a selected slide group on the native festivals. In each case, only the required number of pictures were presented. On the other hand, with a long film-strip of thirty to sixty pictures on Mexico, the temptation arises to show too many pictures at one time. The Individual Film-Slide In working out a solution for these specialized demands, I have prepared an individual slide 2 x 1 5/8 inches as standard size. As this size is just one-fourth of the 3j4 X 4-inch glass lantern slide, it is possible to cut the glass slides into smaller sections and make positives direct on the glass slide or use the clear cover glass for mounting positive n o n-inflammable film-slides. A strip of filmslides can be quickly cut up and secured on these small glass mounts with the usual lanternslide binding tape. Only one piece of glass 2 by 1 5/8 inches is requrred, with the positive film slide mounted on one side and the emulsion side next to the glass to insure complete protection. A protective varnish may be applied to the back of the mounted film-slide for additional protection when the slides are to be used many times. A special slide-holder can easily be made to contain two of these small slides for use in the Leica projector, which is the only film-slide projector which can be easily adapted to this change. In preparing the projector for use with the special slide-holder, the glass pressure-plate is left in its forward position and the film-roll holders and the mat slide are withdrawn. If any light shows from below the slide frame when placed in position, a small card about 2 X ^ inches in size can be slipped down in place of the mat slide which was withdrawn. The double slide-holder can be 6^ inches lc)ng, l}i inches high, and j4-inch thick. Three grooved wood-holders are fastened to a thin metal strip of sheet steel 34-inch wide. More rigid allmetal holders can also be made. In using the mounted filmslides in the Leica projector, it is pos Figure 2 Willard D. Morgan Showing the film-slide rolls, single film slides, and special film-slide carrier for the Leica projector. silile to obtain any combination desired when giving an illustrated lecture or when showing