Question about Railroad spikes

From: "Claren Taylor Purser" clpurser@vt.edu

I was talking to a blacksmith that works on the historical site of John Deere's home in Illinois and he pointed out that there are lines on the top of railroad spikes. Some have several lines and some just have one. Is there anyone there that could tell me what these lines stand for? They are just raised lines on the part of the stake that is hit to drive it in the ground.

—Claren Taylor Purser, Meherrin, VA