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manufacturing such an article it would be important to know how much of each of the substances which go to make a pencil is to be put into it. To decide this, we must have such a view of it as would show how far the lead or plumbago extends into the wood covering it. Such a view is called a " section," and is obtained by supposing the pencil to be cut horizontally, in the case before us right through the middle of its depth from end to end, the cutting plane dividing the pencil into two halves. This cutting, when the upper part of the pencil is removed, will show at once the extent of the lead, as the "plane of section" will have passed through it. How to give a view of the section of the pencil after being cut will be shown further on. The principle involved in obtaining it is that of assuming the plane of projection or the sheet of drawing-paper to be transparent MECHANICAL AND ENGINEERING DRAWING D a L H i I 1 e Sheet 1 F'uj. -I/ D c . Sheet 2 Fiy. 97