The well-known pencil. But do you know how draws a pencil, why do leaves a mark on the paper?
Earlier someone wrote on a wax tablet simple with a sharp stick. But times have changed, to change the plates came paper and stick replaced the pencil. However, the first pencil was not similar to the modern. It was an ordinary lead wand. She left a mark on the paper, and at the same time on the fingers. Had to put it in the "suit" of the skin.
Modern pencil was also wearing a "costume", only wood. And within this "costume" graphite rod, graphite. In graphite, the atoms are arranged in strict order - layers. In the layers of atoms are close to each other and therefore are very closely related. But between the layers, the distance is greater, and they keep each other not so much. So when you hold the pencil, the layers can be easily pulled off and remain on the sheet. For this reason, the lead breaks easily, it is only necessary to hit or drop the pencil. Here to the rescue of the stylus comes in a wooden "suit", which protects crayon from breakage.
Invented the pencil Czech Th. Hartmut, the owner of a factory for the production of laboratory glassware. Considering one of the cups-crucibles, he dropped it, it broke and without a shard left a clear black mark. Hartmut found that the clay was added graphite. So there was writing graphite rods used today.