Hello - we just bought a 1922 cottage w/ a sleeping porch that is lined with "pocket windows". They each have a hinged door in the sill below them that holds them in place. When you lift the door, you can see down into the wall. I believe the pane is supposed to drop completely down into the wall, but they have no handles, and I'm afraid to lower one down - I might not get it back!

Can anyone explain how they were originally designed to work so I can restore them? Google has let me down.