We have moved into a new home built circa-1940 and we've noticed on
most every door frame on the right hand side there is a small metal
bracket/bar type thing about four inches long mounted horizontally at
about eye level. It's just a bit larger than the thickness of a
pencil. They serve no useful function from what we can tell, and
they've subsequently been painted over, but nobody has been able to
tell us what they are/were.

We see them on the door frame for both the front door and every inside
door as well.

Thanks in advance for shedding some light on this for us!