GLASS SLIDES
Were shown at the beginning of the session and again at intermission.
The image was developed onto a glass plate which has a heat protective clear glass side taped over the top of the image slide .
Heat generated from the carbon arc on the slide machine was quite intense , even though it used a small lamphouse , slides would crack easily if left on to long. Slide sessions consisted of Advertising slides from either Ciril Cornish or Chas E Blanks advertising houses.Adverising slides were later accompanied by a cassette audio tape which was run in conjunction with the appropriate slide giving the patrons an audio commentary as well as the visual image.
Coming attraction slides were shown during intermission , Film distributors supplied slides of coming movies . Cinemas also had in-house slides such as " Intermission" "snack bar open" "Please replace speakers" .
Slide Projectors were very basic , consisting of a lamphouse with a dual slide holder attached to the front. Focusing lens were located between the lamp and the slide holders to give even spread of light to both slides . Light when through the slide and the image was focused through small lens on a stem , one for each slide , and then projected onto the screen . A movable shutter was located behind the slide allowing light to go through only one slide at a time , moving this shutter directed light from one slide to the next giving a "wipe" effect when slides were changed.
Slide could be made up with slide printing cards. Cards were placed into a typewritter and text was typed through ink paper onto a clear gel , this was sandwiched between two slide glasses and taped.
Later model slide machines used xenon lamps and slides were belt fed through the machine lens.
Slides are now a thing of the past , Screen advertising companys such as Val Morgan now prepare all advertising on 35mm film in a commercial form , these are simply spliced onto the feature film , making life very easy for the projectionist !