Mechanical pencil

From Freepedia

A mechanical pencil or propelling pencil is a pencil that does not need to be sharpened due to an internal mechanism that pushes ("propels") graphite through the tip. It was first patented in Britain in 1822 by Sampson Mordan and John Isaac Hawkins. Most models have a rubber eraser on the end.

The mechanical pencil became successful in Japan with some ameliorations by Tokuji Hayakawa, a metal worker who just finished his apprenticeship. It was introduced as Ever-Sharp Pencil. Success took a while since people had to get used to the metal shaft first, which was essential for its long lasting life. It was sold in huge numbers, after a large company from Yokohama once gave a large order. Later Tokuji Hayakawa's company got its name from that mechanical pencil: Sharp.

A number of different types exist:

• Ratchet-based pencils where the lead is advanced by a button on either the end or the side.
• Screw-based pencils where the lead is advanced by twisting a screw, which moves a slider down the barrel of the pencil.
• Screw-based pencils where the lead is advanced by friction with the screw.

Most mechanical pencils can be refilled with more graphite but some less-expensive models, especially screw-based designs, are disposable.

Mechanical pencils are considered to be more environmentally-friendly than conventional pencils due to the fact that wood is not necessary for its manufacture and no wasteful wood shavings are created.