Articles are occasionally required to be made up in the form of an egg-shaped oval; hence a knowledge of how to describe that figure will be useful to a sheet and plate metal worker. The con-struction, which should not be difficult to follow, is shown in Fig. 123. The long diameter is first marked down and the point O obtained by making A O equal to half the width of the oval. The short diameter, C D, is drawn at right angles to A B passing through the point O. A semicircle is then described upon C D. Join B to D and make E F equal to O C by running round the dotted curve and line, as on the figure. Cut off B P equal to D E, and so fix the point P for the centre of the end curve. Join P to E and bisect the line P E in H. Draw H Q square to E P, thus obtaining the centre, Q, for the side curve. Join Q to P and produce to K. The line Q D will now be used as the radius for the side curve and P B for the end curve, both of these curves meeting in K. The object of putting in the line Q K is, of course, to determine the meeting-point of the side and end curves. If the construction is carefully carried out there should be no difficulty about the curves meeting at the point K. Fig. 123.