Need help identifying hardware on Derby desk [repost edit]

I have a small Derby desk with two mysterious buttons on the drawer support (towards the ends) below the middle drawer, between the two side cabinets. It seems to have been an electric switch of some kind at one point, with screws to hold wires on the back side. It is the only hardware that isn't the same kind of brass used on the rest of the desk.

If anyone has seen these before and/or knows what they are please let me know, it would be very much appreciated.