E. H. Sheldon & Company Desk

I think this might be a Drawing Table, however, this piece has the six slots in the center that the drawing table does not show. It appears that these "slots/slides" were added after the manufacturing as they are not evenly lined up to the sides.
Wondering specifically what type of desk this is as per the E.H. Sheldon Company. In other words, what was their name for it per their catalog.
The desk is approximately 41" H x 38" W x 24 1/2" D. It has six locking drawers down the right side. I has six openings in the front where I suspect thin drawers previously were.
What is missing from the center section? Or do you think these were added later?
Where might I find more information regarding the E. H. Sheldon & Company?
I'm curious when the desk was manufactured.
It looks very similar to their Watchmaker's Bench, however, it would not be advantageous to the watchmaker to have a top that rises. It would actually make the job more difficult to work on a slanted surface as his pieces would slide down.