Magnetic Recording Handbook - Camras - Google Books

https://books.google.de/books?id=PdruCAAAQBAJ&pg=PA8&dq=%22Telegraphie-Patent-Syndikat%22#v=onepage

When I started in magnetic recording nearly fifty years ago, it was easy to perceive the common sense of it. There was very little mathematics and every new finding was a source of wonder. I have tried to recapture this spirit with simple explanations,…