A little research tells me this was the interior panel on the door of a Victor safe, last decade 19th century. I just thought--think--it's a great looking thing, to hang as a sign of sorts now, with a sort of trompe l'oeil aspect to the "silent" slate bearing the years of patents in a calligraphic font. Graphically satisfying, an icon of safe-keeping, and somehow it all feels a bit Duchampian to me. And of course I love a school slate!
13 15/16" x 8 7/8". Lithograph on what I believe is steel, it is quite heavy. Some surface scratches as evident, but still very sharp looking; photos don't quite convey either the visual punch or the objecthood of this, but it is substantial and really quite a nice thing.