I believe it is a typical by-product of the steel manufacturing technique for small batches production in the late 1800's. Prior to widespread adoption of Bessemer's Converter and crucible steels a different technique was used. It was known as fa-g-g-oting (strange but true) Iron rods were drawn from pure puddled iron. @ 1/2" diameter. The rods were then case hardened by cementation method for @ 24 hrs to infuse carbon into the iron.After case hardening they where cleaned off, fluxed and bound together into a bundle(fa--ot) of 10-20 rods. then heated to white heat and pounded together. The end result was a billet of steel. Incidentally the Birmingham gun quarter was/is bordered by Steelhouse Lane which reflects a business that performed this method.The marks one sees are the boundaries between rods. As a production technique it disappeared around the year 1900.
