A question for the trainers out there, Whilst clearing out my partners attic we found an overhead projector. Not the normal backlit type for accetates but one on which you could place books, pictures, pretty much anything that would fit. A strong light is then focused on the subject and the mirror image is restored and projected. I have a faint memory of these things being discussed when I did my teacher training and if I remember correctly they were fondly remembered for setting fire to what ever was put on the display plate if not monitored carefully. Does anyone know what these contraptions were called?

Seem to remember that whatever it was called it finished with -----ascope?

Got it in one well done John C