Turns out, it is an attic fan from Sears (dates back to ... hmmm... based on the wood paneling, I'd guess 1978-1984). I got curious and found this website:
It's basic operation works like this:
Talk about going green!
We normally would keep the thermostat at 69-72 degrees at our old apartment.
Since moving to the house, we've been at about 75 degrees. Last night was our first cool late summer night here in Florida, so Paul opened all the windows and turned the attic fan on. I tell you what, I was freezing! It creates the best drafts ever. Keep your ceiling fan on with it, and it's like a 65 degree air conditioning using almost NO electricity !! I had no idea these things existed, but now that I do, and now that I see other things around this house the previous owners had done, it looks like people have been "going green" ever since olden days when there WAS no other choice! I am so excited about this concept! I will keep this an open forum for green living.
Like our sprinkler system that runs from a well/spring in the backyard (haven't figured that one out yet, but I can hear it. I'll have to order plot drawings from City Hall)