Excursions in Science!
These gifs come from a 1935 educational film made by GE called Excursions in Science. The company presented some of the science and technology its researchers were developing, along with the era’s state-of-the-art manufacturing processes.
At top, researchers present toothless gears, which are magnetic wheels that spin based on attraction and repulsion at their poles. The display showed off a new alloy that could be magnetized in sections, a significant innovation over iron magnets. The wheel on the left has two poles. The central one has four. The right has six. Since like poles repel, the three wheels created a magnetic gear train when the first was spun.