More related to metronomes coming into phase with each other than your semaphore problem, but... for your viewing pleasure: https://www.youtube.com/watch?v=e-c6

More related to metronomes coming into phase with each other than your semaphore problem, but... for your viewing pleasure: https://www.youtube.com/watch?v=e-c6S6SdkPo https://www.youtube.com/watch?v=e-c6S6SdkPo