. Model drawing and shading from casts; a complete guide to the elementary and advanced examinations in these subjects; . 1/ \ in drawing the ring and jT^r-- ; ^—r^ any figures in which con- ^ /^^^T^^^ centric circles occur it must / be taken account of, and if the drawing is on a ^° ^* large scale it will be necessary to draw a new diameter for each ellipse that is required. It has been pointed out that a circle seen edgewaysexactly opposite to the eye appears to be a straightline, whether it isplaced vertically, hori-zontally, or you will hold athin circular disc ofcard, or
. Model drawing and shading from casts; a complete guide to the elementary and advanced examinations in these subjects; . 1/ \ in drawing the ring and jT^r-- ; ^—r^ any figures in which con- ^ /^^^T^^^ centric circles occur it must / be taken account of, and if the drawing is on a ^° ^* large scale it will be necessary to draw a new diameter for each ellipse that is required. It has been pointed out that a circle seen edgewaysexactly opposite to the eye appears to be a straightline, whether it isplaced vertically, hori-zontally, or you will hold athin circular disc ofcard, or a penny, ineach of these severalpositions and gradu-ally remove it, higher j,^^^ , lower down, or further to the right or left hand, you will find thatthe further it is removed from the eye the rounderit will appear. Then if we suppose a cylinder, a fewinches below your eye, it is evident that the lowercircular surface is further from your eye than the topone, so it will be rounder, and the same result willbe obtained if we suppose the cylinder raised so thatthe bottom of it is above the horizon, only now it. 54 MODEL DRAWING AND SHADING FROM CASTS. is the top curve wMch is further off and consequentlythe roundest. Make the experiment with the cylinderplaced horizontally but obliquely, and you will findthat although the farther end of the model is relativelysmaller, it is also proportionately rounder, hence we may-say, that the hidden curve of all circular figures isrounder than that of which the whole ellipse is does not, of course, apply to circles which showtheir true shape. In drawing circular models, it is always safest todraw the whole of the ellipse which is partially hiddento avoid the risk of the error illustrated in this draw-ing of a cone, where it will be seen that if the curveBC were reversed, a corner would occur at b and dotted line shows the com-A A pleted ellipse of which bo is a /\ part, and consequently abc is / \ really a drawing of a
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Keywords: ., bookcentury1800, bookdecade1890, bookpublisherlondonchapmanandha
