Semaphore Trainer, US Navy H-21 and can be seen behind

and can be seen behind the cockpit of many allied fighters and mid spine on multi engine aircraft

The fluid in the floating ball chamber is no longer present

there is not a single cosmetic flaw discovered in our examination of the artifact

Journal of Navigation

with a control panel

Semaphore Trainer, US Navy H-21 and can be seen behindHere is a very interesting device, a Semaphore, or Flag Signaling, Trainer, made for the US Navy Special Devices Center by the advertising promotional firm Einson Freeman, Inc. The device is a rotating training card within a card. The "Sender" view is on one side and the "Receiver" view on the reverse side. When rotated to the desired letter by the Sender, he see's which flag arm position must be taken to communicate that letter. The Receiver, upon