The educational screen (c1922-c1956])

September, 192s Lantern and Slide 363 ented device sold by the dealers is a pad of "L" shaped half-mats covered with parallel lines by means of v^hich any size of rectangular opening can be readily and accurately secured. The objection to this arrangement is its cost and the time it takes to apply. In our laboratory we find the quickest and best method is to cut a binding strip into four pieces and after dampening slightly place these on the emulsion on the four sides of the picture as desired. On top of this a standard mat with a large opening is placed and the whole bound up. Great pains must always be taken to produce clean edges, parallel sides, and square corners, as a defect which is hardly visible in the slide itself becomes enormously exaggerated on projection. Binding is another simple problem but one which apparently offers great difficulties to the beginner. While the binding of the slide in no way affects its projection quality, provided the paper is securely attached to the glass, it is a very simple matter, if properly done, to secure a neat and durable result. There is no necessity or even advantage in cutting binding strips into short pieces. If the strip is properly gummed and moistened the glass 'can be placed on it squarely and the slide revolved till the binder is fully attached, and by pinching down the corners without cutting them away, we leave an additional thickness of paper at the corner; Frequently in handling, sHdes are stacked and these reinforced corners serve to keep the glass surface from coming in contact and thus prevent scratching and dulling of the surface from rubbing against other slides. To the operator the most exasperating feature of the ordinary slide is the thumb label, or to speak more correctly the lack of it. To the man in the booth a slide without a thumb label is worse than no slide at all; and on the other hand, a thumb label properly placed enables him to quickly and accurately place the picture on the screen right side up and right way around. Many lecturers hand their slides to the operator with the statement that they are "all in position, right side up and in order, and thumb labels are not necessary," but with the greatest of care this method results in mountains standing on their head and other abnormalities. If the thumb label were a difficult or expensive thing to apply, there might be some excuse for its absence, but it is possible to label an entire lecture set in a very few moments and there is no excuse except carelessness for not so doing. This label also serves to Please Write to Advertisers and Actual photograph in brilliant sunshine in classroom of a hading colkge. Daylight Projection with the SPENCER DELINEASCOPE and the TRANSLUX SCREEN The above outfit in your Classroom means No Darkened Rooms Open Windows Perfect Ventilation No Eyestrain Wide Angle of Vision Write for: "The Tvoo Pamphlets" SPENCER LENS CO BUFFALO, NEW YORK New York, N.Y. San Francisco, C»L Mention The Educational Screen