. The practical draughtsman's book of industrial design, and machinist's and engineer's drawing companion: forming a complete course of mechanical, engineering, and architectural drawing . employed in architecture,and is thus drawn:—The axes, ab and CD, fig. 1,being given, per-pendicular to each other; with the point of intersection, o, as acentre, first describe the circle, CADE, half of which forms theupper portion of the ove. Joining b c, make C r equal to b e,the difference between the radii, o c, o b. Bisect F b by the per-pendicular, G H, cutting CD inn. n will be the centre, and h cthe
. The practical draughtsman's book of industrial design, and machinist's and engineer's drawing companion: forming a complete course of mechanical, engineering, and architectural drawing . employed in architecture,and is thus drawn:—The axes, ab and CD, fig. 1,being given, per-pendicular to each other; with the point of intersection, o, as acentre, first describe the circle, CADE, half of which forms theupper portion of the ove. Joining b c, make C r equal to b e,the difference between the radii, o c, o b. Bisect F b by the per-pendicular, G H, cutting CD inn. n will be the centre, and h cthe radius of the arc, c J; and I, the point of intersection of hcwith a b will be the centre, and I B the radius of the smaller arc, I B K, which, together with the arc, n K, described with the centre,l, and radius, l d, equal to H c, form the lower portion of therequired figure; the lines, on, L k, which pass through therespective centres, also cut the arcs in the points of junction,j and K. This ove will be found in the fragment of a cornice,fig. Ik. A more accurate and beautiful ove may be drawn bymeans of the instrument represented in elevation and plan in theannexed The pencil is at a, in an adjustable holder, capable of slidingalong the connecting-rod, b, one end of which is jointed at c, to aslider on the horizonfal bar, d, whilst the opposite end is similarlyjointed to the crank arm, e, revolving on the fixed centre, f, onthe bar. By altering the length of the crank, and the position ofthe pencil on the connecting-rod, the shape and size of the ovemay be varied as required. 9 51. The oval differs from the ove in having the upper portionsymmetrical with the lower; and to draw it, it is only necessary torepeat the operations gone through in obtaining the curve, lbh,fig. 1. 52. The ellipse is a figure which possesses the following pro-perty :—The sum of the distances from any point, a, fig. 2, in thecircumference, to two constant points, b, c, in the longer ax
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Keywords: ., bookcentury1800, booksubjectdecorativearts, booksubjectdrawing
