The audio-visual handbook (1942)

96 The Audio-Visual Handbook filmslides carried in stock by the producers and distributors range in price from $1 to $3, with the majority listed at $2. The United States Department of Agriculture, through its extension service, offers a very economical filmslide service to those who may be interested in material for use in teaching agriculture in its many phases. The department has prepared many sets from its vast library of photographs, and these special sets are listed in mimeographed catalogs and are priced generally from fifty to seventy-five cents a roll. It is not claimed that this low price represents the full cost of these special and often very valuable agricultural filmslide productions, as the Government absorbs the overhead, postage, and distribution costs. But it has enabled many schools offering vocational agriculture courses to purchase a considerable quantity of this material and establish filmslide libraries for permanent use, when they otherwise could not have done so. Other Government agencies have filmslides available and are glad to have them used among schools. A list of sources of filmslides of various kinds will be found on page 218 of this book. The majority of the organizations listed have subjects available in various fields and will be pleased to send complete information upon request. Microfilms "Microfilm" is the name generally applied to a very small photograph of a much larger printed page — check, annotated drawing, well log, or page of a book, magazine, or newspaper. This miniature photograph, on either 16 mm. or 35 mm. film, may then be enlarged through projection to a convenient reading size. Libraries use the process to copy rare books and manuscripts, thus saving the originals from dangerous handling. Banks use the process to copy and preserve records of checks and deposits. Other business houses use it to copy and preserve important documents. Hundreds of pages of valuable information may be recorded on a small roll of film and read or reproduced as desired. Microfilming in recent years has developed to a point where the material is becoming available to small school libraries and where microfilms can be made quite easily by using compact, simple photographing equipment. The new microfilm readers have been designed to meet the demands of the small library as well as the larger reference library. In addition, they are especially suitable for use by business houses which microfilm their permanent records. The field of micro