Hugh Thompson found this at a sale.
It's a six-sided brass rod, 13mm dia (ie corner to corner) 250mm long, with a "pencil" point at one end. The other is drilled for string. It has a leather case that looks professionally made, though that includes making by the local cobbler.
It doesn't work well as a plumb-bob as it does not hang straight; this is I think an inherent problem of the long thin geometry; could plumb bob fans comment?
{gallery}Queries/2015/Brass_rod{/gallery}
Any ideas on what this was used for are welcome.
Hugh Thompson