This wartime tool helped train naval personnel by showing the various flag positions used in semaphore signalling.

A combination of two disks with letters allowed a user to learn the positions in which flags were held to make signals. In this case, the flags are indicating the letter "C". The view on the left shows the arm positions as they would appear to somebody receiving the letter, while the view on the right shows how they would appear to someone sending it. Even though radios were widely used during the Second World War, semaphore flags remained an important means of communication.

1999.20.87
Bouchard Collection
Naval Museum of Quebec