A longitudinal groove, apparently ground into one side of the needle, lengthwise, by means of a small grinding-stone and emery powder, ran for a quarter of an inch above the point.

This groove seemed to me to have been produced by an amateur, though he must have been one accustomed to delicate microscopic manipulation; for the edges under the lens showed slightly rough, like the surface of a file on a small scale: not smooth and polished, as a needle-maker would have left them.

I said so to Hilda.
"You are quite right," she answered.

"That is just what it shows.

I feel sure Sebastian made that groove himself.