Mechanical pencil
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. Most models have a rubber eraser on the end.
The mechanical pencil was first patented in Britain in 1822 by Sampson Mordan and John Isaac Hawkins. Between 1820 and 1873, more than 160 patents were registered pertaining to a variety of advancements or improvements to mechanical pencils. The first spring-loaded mechanical pencil was patented in 1877 and a twist-feed mechanism was developed in 1895. The 0.9mm lead was introduced in 1938, and later it was followed by 0.7mm, 0.5mm and 0.3mm versions.
The mechanical pencil became successful in Japan with some ameliorations by Tokuji Hayakawa, a metal worker who had 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.
- Twist-based pencils advance upon twisting the head of the pencil. Many of these will have a locking mechanism one way to allow the lead to be pushed back into the pencil.
Most mechanical pencils can be refilled with more graphite but some less-expensive models, especially screw-based designs, are disposable.
References
- Deborah Crosby, Victorian Pencils: Tools to Jewels, Schiffer Publishing Ltd., Atglen, PA, 1998.
