. Teacher's manual for freehand drawing in intermediate schools. are often employed in design. An Ellipse.—An ellipse is a j^lojie ^figure boundedby a curve, every jjoint of ivhich is at the same com-bined distance from tico j^oints called the foci.(Seep. 116.) According to this definition, the space bounded bythe curve, and not the curve itself, is the the word ellipse, like the word circle, is,for convenience, often used to describe both thecurve, and the enclosed space. The ellipse being a mathematical figure, it can bedrawn with perfect accuracy only by mechanicalmeans. There a
. Teacher's manual for freehand drawing in intermediate schools. are often employed in design. An Ellipse.—An ellipse is a j^lojie ^figure boundedby a curve, every jjoint of ivhich is at the same com-bined distance from tico j^oints called the foci.(Seep. 116.) According to this definition, the space bounded bythe curve, and not the curve itself, is the the word ellipse, like the word circle, is,for convenience, often used to describe both thecurve, and the enclosed space. The ellipse being a mathematical figure, it can bedrawn with perfect accuracy only by mechanicalmeans. There are various ways to do this. One isdescribed in the Primary Manual; 30U should makeyour pupils familiar with this way if they do notalreadv understand it. Here is another : — 112 TEACHERS^ Drawing the Ellipse by Mechanical Means. Directions. —Draw two straight lines, 1 2, 3 4, of indefinite length, mntnal-\y perpendicu-lar, and bisect-ing each the pointof bisection, o,mark off oneither hand,along one of thelines, as at 1and 2, the samedistance, name-ly, one-half ofthe long, ortransverse, diameter of the proposed ellipse. Call it twoinches in the present case, making the whole distance, 1 2,equal to four inches. From o. on either side, mark off alongthe other line, as at 3 and 4, the same distance, namely, one-half of the short, or conjugate diameter of the proposed el-lipse. Call it one mch, makmg the whole distance, 3 4,equal to two inches. You now have the diameters of the proposed ellipse. Theone, 1 2, is twice as long as the other, 3 4. Any other pro-portion con Id be taken as well. The ends of these diametersgive four points in tlie required curve. For one skilled indrawing ellipses freehand, these points would suffice ; but forthe beginner they are no
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectdrawing, bookyear1876
