Smoke detectors date back to pre 1900, the basis of the version we still use to this day since something like the late 1930's. Been a while since I was in fire school but I know damn well we had them growing up in 1978 as I set it off.....
I had to smile about you setting off the smoke detector. It makes no difference when they were invented. I never heard of them at the time and the owner did not have them installed in that mobile.
