Antique incubators

[bassbaby5300]

I inherited two antique incubators from my grandfather. I have the first one restored and would like some info on it if anyone knows about it. How old is it ? It seems to be complete except for one piece which sat on a platform inside the top and stuck up through a hole in the top and had something to do with the adjustment screw on the thermostat arm. Anyone know what I'm talking about ?

 

[Tabasco Jack]

Have one that is similar. https://www.backyardchickens.com/articles/the-new-old-buckeye-incubator.72707/
My best guess is that mine was made between 1920 and 1940.
If you look at my article and scroll down, there is a photo of the inside that shows the metal thermometer apparatus. However, mine is on the side. There is a screw that attaches to the apparatus and goes through the counterbalance. Inside heat moves the apparatus which moves the cover on the chimney raising or lowering the heat.