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FIRST PRINCIPLES OF Fi(J. 199 Fig. 200 MECHANICAL AND ENGINEERING DRAWING 203 faint lines parallel to the axis a a. At any point, s in bd, draw the line s I at right angles to a a, and produce it indefinitely. From the points in s I where the meridians 1, 2, 3, etc., cross it, set off on each of these respectively, the lengths of the ordinates in the semi-circle measured from b c, and through the points thus found draw the semi- elliptic line as shown. Then, for the development No. 2, on the produced line through s I in No. 1, set off from I to #', the distances that the points 1, 2, 3, etc., in the semi-ejlipse s4, No. 1, are from each other, and through the points thus found, draw lines parallel to the side e I c of the cylinder. These lines will be the meridians shown on the front surface of the cylinder when it is laid out flat ; for those on its near face, set off the same spaces from s to I' as for the front face, and draw in the meri- dians as shown. For the development of the top and bottom edges, draw projectors through points 1, 2, 3, etc., in them, in No. 1, to cut the corresponding lines in No. 2 ; a continuous line drawn through the points of intersection at both ends of the meridians 1, 2, 3, etc., will be the edges required. If the extreme meridians, e'l'c', be put in full, as shown, the figure bounded by the lines ede, cb c', and e I c, e'l'c', will be the complete development of the curved surface of the oblique cylinder dbce, No. 1. If the student now compares this development with that of a por- tion of the surface of the right cylinder, lying between the two