The Boatswain's Call, or Boatswain's Whistle, has been around, with little change in basic design, for at least several hundred years. I have found references dating back well before 1400. 30 minutes of searching the Internet could garner you quite a bit of information, now that you know what it is.
The piece you found appears to be based on a modern design used by several navies around the world. If an official issue of the U.S. Navy, it will be marked such. Many sailors skilled in its use prefer models made of Sterling over the more common copper/nickel alloy due to the quality of the tone.