Mechanical Pencil and Who invented it?

Mechanical Pencil and who invented it?

Propelling / Mechanical Pencil

 We all know and use the convenient mechanical pencil. It doesn't need to be sharpened after some use, so the standard wooden pencil sharpener becomes useless too. While there are leads in the tube we have nothing to worry about. Most of them come with rubber eraser at the end which make it's use a real pleasure. See how the graphite stick become wooden pencil and the wooden pencil become mechanical one. Hope to read your comments on everything writing instruments related.