found school desks with American Screw box

I picked these up from some rich guy who I was moving who didn't want to throw them out. He wanted someone to take them, fix them and make some money. So I helped him out. I did a light restoration on them. I scraped off the years of kiddy glue and glitter and boogers and gum and sanded them down enough to put a mission oak stain on them. They look older now than they did. I removed about 12 layers of rust and bad paint from the iron but left them alone instead of repainting. I keep the original boards they were mounted on and cleaned up the original screws. I know they were original because whoever put the desk together used the top of the screw box to level the desk and legs. The box said 7/8 #11 Bright from American Screw Co. Patent 1883. The screws were slotted not Phillips, which came after 1933, so I have an idea about how old the desk is but I am not for sure seeing how I have not been able to find any photos of this type of desk. I am hoping that someone can shed some light on when and where this desk was made. I would be more than happy to provide any additional info or photos.
Thanks,
random.hamilton@yahoo.com