Have you a lead-pencil? If not, I want you to get a loan of one, and to look at it very carefully. It is made of wood—most likely of cedar wood, for the wood of the cedar tree is much used for making pencils.,
Do you see the name of the maker in bright letters on the side of the pencil? You may see, too, the letters H for hard, B for black, or HB for both hard and black, which are stamped on the pencil. From these marks you know what kind of pencil it is.,
The pencil is a round piece of wood, is it not? At each end of the pencil you can see a small square of black-lead. Now, how did the black-lead get there? Did it grow inside the wood?,
Look very carefully at the ends of the pencil. Ah, you see! it is made of two strips of wood, which were glued together after the black-lead was put in.,
读书笔记
是否公开
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试试把这支铅笔拆开。把铅笔在水里泡一会儿,胶就变软了,两片木头就会分开了。,
读书笔记
是否公开
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Try to pull your pencil to pieces. If you put it in water for a while, the glue will become soft, and the two pieces of wood will come apart.,
Then you will see that a neat little hollow was made in one of the pieces, and that a little strip of black-lead— of just the right size—was put into it. The other piece of wood was then glued over it, and the pencil was made round and smooth.,
When you rub the point on a piece of paper, little bits of black-lead stick to the paper and make black marks. In this way the black-lead pencil is very useful for writing or drawing.,
Before you use your lead-pencil, you must sharpen one end of it with a knife. The wood will not make a black mark,so it must be cut away. Then the black-lead is left sticking out by itself to make black marks on the paper.,