Okay I am piling together information to do a write up of the Denver Siren for the Wiki, and there was some word a long time ago, that this particular siren could possibly be a Denver siren (based on lettering cast into the side.) Has anybody ever figured it out? Credit to kx250rider (Charles) for the pictures..
And to Charles, if you see this, any chance you could get up there in the near future to confirm my suspicion, and maybe a few more pictures and angles? To my knowledge, Denver only had horizontal sirens up until Hendrie & Bolthoff MFG and Supply sold the patent to Sterling sometime in the early to mid 1920's in which it was no longer known as a "Denver" siren
SOLVED. Thanks to Facebook user Aaron Allevato the siren in question has been determined to be a Pearse Company siren, a manufacturer based out of Denver Colorado. See pictures further in thread.