Visible incubator (Apr, 1948)
Though his plan for a mass market chicken rotisserie was a failure, Katay found that replacing the chickens with little wooden soccer men made for a delightful game. Which he promptly named after his (now-ex) girlfriend Foos.
Visible incubator gives you a look at baby chicks hatching. All phases of birth from first peck at shell to day old chicks are visible.