Who knows what this is?

[math311]

This klaxon thing will produce the distinctive wail of an air raid siren and appears to be quite old. We are using it on a float for a parade, and we would like to know what it might really be called. The little metal plate says it is an "automatic burglar alarm". A kid also brought in some 2 Mb hard drives from long ago. I guess i cant upload a pic, but it has an electric motor on back, an air intake section with spinning fan/blades, and a bell that opens big. 12 volts