The audio-visual handbook (1942)

Types of Visual Aids and Their Uses 95 these projectors, known as Tri-Purpose projectors, also accommodate the miniature glass slides made from individual frames by camera enthusiasts who have discarded the poorer frames from their film 300 -watt Tri-Purpose Projector Equipped with HeatRay Filter Photo Courtesy Society for Visual Education, Inc. strips, or by instructors who are building a collection of selective lecture illustrations. Double-frame filmslide projectors do not exceed the others in price, as a rule; and the combination Tri-Purpose models just described are available from $38.50 to $65.00, complete with carrying case. A list of manufacturers of filmslide equipment may be found on page 218. Sources of Filmslides. There are several producers of both stock and special filmslides, and some maintain large libraries of this material on thousands of subjects. The two largest such libraries in the United States were combined in the summer of 1936. There is a combined catalog compiled and published by the Society for Visual Education, Inc., Chicago, which lists the filmslide subjects of all the larger producers of filmslides for the general school field as well as subjects for use by churches, Boy Scouts, etc. There are many sources from which filmslides may be secured on loan or may be purchased. Several of the University Extension Divisions have full libraries of filmslides for loan to schools. Some industrial organizations from time to time arrange for the production and distribution of valuable filmslide sets among schools at little or no cost*. The average strictly educational *Free filmslide distribution to schools has usually been made through the Society for Visual Education, Inc., Chicago.