In the early 1900s all across the southern united states sawmills cut the last of their timber and were abandoned. To get the timber from the woods to the sawmill, the mills would lay miles of tram tracks. Some people may call this narrow gauge track. It was about 1/3 the size of modern...
I recently found this piece at a sawmill/lumber yard site from the 1920's. At first I thought it might be a cover to a light from a truck or vehicle. The little posts on the inside don't have threads so I'm not sure what it went on. It measures 3-1/2" x 4". It was quite rusty when I found it...