I've been to the Fishers fire hall in Victor, NY a few times and noticed an old omnidirectional siren on the roof. I have no idea what this thing is: https://goo.gl/maps/4fV5CNy6F7jWdEFT8
It might look like a boiler stack, but it's a siren - there's a chopper there, though I can't tell if it's single or dual-tone. The chopper is on top under a shallow conical housing with its motor beneath it. The motor housing appears to have a fish scale-type texture and shaping. I don't think it's run in years as I never heard it for fire calls any time I was working near the fire station.
Any ideas what this is? Perhaps the WNYSirenGuy might be able to swing by there and get some pics as I don't work near there anymore.