bigjohn, you mean primitive as in age or design? Or both? lol
Yours is cool, what do you think it came off of? I've seen a couple on piano stools or tables before but those are only about an inch or so.
The 78 meaning 1878 puts it in time frame for a handmade but instead of "Patent April 4 1878", maybe it's "patent applied for (4) 1878". Who knows, could be wishful thinking on my part and it's just some sort of manufacturer code that's partly illegible from the rust. but I'd love to know what they were originally mounted to.