Mechanical Pencil

Mechanical Pencil

A mechanical pencil (US English) or a propelling pencil (UK English) or a pen pencil (Indian English) is a pencil with a replaceable and mechanically extendable solid pigment core called a lead. The lead is not bonded to the outer casing and can be extended as its point is worn away. The lead is actually made of graphite or a solid pigment.
Mechanical pencils are used to provide lines of constant thickness without sharpening in technical drawing and writing. They have also been used for fine-art drawing. They are also popular with students, since they do not have to be sharpened and have a softer feel than a regular pencil. Mechanical pencil lead is usually identical in density, but not in thickness to a traditional HB (US #2) pencil lead.
Mechanical pencils were first used in the 18th century with many designs patented in the 19th and 20th centuries.

#HISTORY
Conrad Gesner described a leadholder pencil in 1565, but the lead had to be manually adjusted to sharpen it. The earliest extant example of a mechanical pencil was found aboard the wreckage of HMS Pandora, which sank in 1791.
The first patent for a refillable pencil with lead-propelling mechanism was issued to Sampson Mordan and John Isaac Hawkins in Britain in 1822. After buying out Hawkins' patent rights, Mordan entered into a business partnership with Gabriel Riddle from 1823 to 1837. The earliest Mordan pencils are thus hallmarked SMGR. After 1837, Sampson Mordan ended the partnership with Riddle and continued to manufacture pencils as "S.MORDAN & CO". His company continued to manufacture pencils and a wide range of silver objects until World War II, when the factory was bombed.
Between 1822 and 1874, more than 160 patents were registered pertaining to a variety of improvements to mechanical pencils. The first spring-loaded mechanical pencil was patented in 1877 and a twist-feed mechanism was developed in 1895. The 0.9 mm lead was introduced in 1938, and later it was followed by 0.3, 0.5 and 0.7. Even 1.3 and 1.4 mm mechanisms were available, and 0.4 and 0.2 versions are now produced.