who unwinds the cord will find, that, with each suc-ceeding revolution, he inqreases more rnpidly his dis-tance from the cone, his path being that of the va-riable spiral (J). To construct a spiral of this character, draw twostraight lines, o and /, crossing each otlier at right-angles cite. Draw… … the right of the line p f, as at a for example, draw the line a b, parallel with theline p f. From the point b,wliere the line a b touches theoblique line t, draw b d paral-lel with the line o. From thepoint (/, where the line h dtouches the oblique lines, drawa vertical line downwards untilit…
Drawing -- Study and teaching
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