When did the simple pencil appear? Detailed answer

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When did the simple pencil appear? Detailed answer

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When did a simple pencil appear?

Simple pencil. Here it is on the table in front of me. Black heart, wooden shirt. Why is it called simple? Because it is very simply arranged, and also because it is easy for them to draw a line on paper. And such a pencil appeared quite recently, in the XNUMXth century.

The core of a pencil is made from a mixture of graphite powder and clay. This mixture is prepared in the following way. First, graphite is finely-finely ground - many times finer than cosmetic powder. Then it is mixed with clay. If a hard pencil is made, clays are added more, and if soft, less. This mass is pressed through special narrow holes to obtain rods, then these rods are dried in special ovens. Now you need to "sew" clothes to the pencil. They make it from wood: cedar, poplar, linden, alder. Small boards are cut out, which must first lie down and dry. Then six grooves are made in them, where the slates are laid, as if in cribs. From above they are covered with the same planks and glued, pressing the planks to each other. When the boards stick together, they are cut into six blanks. The blanks are sanded, painted four times and varnished twice. And now the pencils are ready!

According to the "character" pencils are different: some have a soft, gentle "heart", others have a hard, like flint, and there are pencils of medium hardness. This is evidenced by the marking that is affixed to the pencils - letters and numbers showing the degree of hardness or softness.

Reliable pencils will help you out when the pen can be capricious and refuse to work. Scuba divers take them with them to make sketches underwater. Even weightlessness and frost do not have a detrimental effect on them! So in space and at polar stations you can’t do without them.

Author: Cellarius E.Yu.

Random interesting fact from the Great Encyclopedia:

Where do rheobatrachus frogs develop and where do they come from?

In Australian rheobatrachus frogs, the laid eggs are swallowed by the female. Eggs, and then tadpoles, develop in the mother's stomach, feeding on the secretions of its mucous membrane. The grown frogs gradually move into the oral cavity of the parent and finally come out of captivity to freedom.

Since the female cannot feed during the rearing period (otherwise she would have digested her young), her digestive glands are completely disabled during this period.

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