Old Unknown Household Heat Detector

Has anyone seen anything like this before? I think it may be a heat detector of some sort, judging by what appears to be a bimetallic strip below the battery terminals in the third photo. I’ll upload a demonstration video at some point once I find the time.

Woah that looks very cool! That is a really great find!

I’ve never seen any examples of that alarm or the Detexall brand, but the American LaFrance stamp on the inside caught my eye.

American LaFrance manufactured fire engines, rescue vehicles, etc. going all the way back to the steam-powered engines of the late 1870s, before filing for bankruptcy a few years back.

I wonder if this was simply an accessory licenced by the company, or if it was actually produced for and installed in a firefighting vehicle.