What is this?

[Mister_Penetrator]

On this website: http://www.sirenworld.tk/ under siren data, there is a picture or two of an Australian siren. Does anyone know what it is?

[SirenMadness]

I guess that the device you're stating must be a siren, by the fact that it was used in the second World War, which necessitates a siren-based signal being used for civil defense. I also guess that this thing could be a horn, a horn working in the same way as the Diaphone, seeing that there is probably some mechanism for vibration on the top of that thing, and having such a beefy mechanism for rotation gives me a citation that there is some very good sealing involved, as horns use up allot of air, compared to sirens.
Wait a second, though.. didn't someone show a picture of this thing inside a room, confirming that it's a horn, on the old board?