One of my facebook group's member posted these pictures, he found them in their garden buried. He made cleaning, and they look old, but are they from 1880's? If the location helps: it is in Hungary, and many of tools were made in Germany.
So far my research tells that 1880's in US they had square shaped screw heads, not hexagons like today. But I am still unsure.
It is entirely possible - Hex-head bolts were known well before that. This page states that James Nasmyth made a lathe attachment to mill hex nuts in 1830, and by the 1880s the combination of cold-heading and the Bessemer process were being used to mass-produce them.
That "1881" looks hand-inscribed to me. Simple tools aren't commonly serial numbered in my experience.
The number could be a date added by the owner, or it could be some other numbering: a bench number where he worked, his employee number in a factory, or something like that. People in a factory tend to borrow tools and "forget" whose they are, so marking them is wise.
