"William Noble" wrote in
:

I have one of those exact stones sitting here, new and unused, in a
box - it says "norton abrasives", "Safety blade hone VS 1" it has an
instructoin sheet, and the stone is green colored. it isn't really
hollow ground (I've seen those too) - this one has a shallow "V" in it
- same principle.


What you have is a "Fisherman's" stone - the "V" is used to sharpen fish
hooks.

It can also be used with single-edged razor blades by placing the blade
(including the back) flat on the stone. (The back sets the angle for the
cutting edge.)

The "hollow ground" stone was for double-edged blades: the pressure of the
finger against the center of the blade (needed to press it into the hollow)
helped to both provide adequate contact between the stone and to insure
that the angle of the blade was maintained.