Transmitting Photos by Phone
Recently I watched a 1930s film about how photographs were transmitted by phone. What makes this feature so interesting is that it is explained in a simple to understand manner, using, string that has an image, of all things. This is a clear explanation of how image sending works, but also how television and other technologies would work in year to come. https://www.youtube.com/watch?v=cLUD_NGE370
This is about the analogue sending of an analogue image.