PROBLEM V. To draw a Horizontal Line, given in Position and Magnitude, by means of its Sight-Magnitude and Dividing-Points 24 PROBLEM VI. To draw any Triangle, given in Position and Magnitude, in a Horizontal Plane 27 PROBLEM VII. To draw any Rectilinear Quadrilateral Figure, given in Position and Magnitude, in a Horizontal Plane 29 PROBLEM VIII. To draw a Square, given in Position and Magnitude, in a Horizontal Plane 31 PROBLEM IX. To draw a Square Pillar, given in Position and Magnitude, its Base and Top being in Horizontal Planes 34 PROBLEM X. To draw a Pyramid, given in Position and Magnitude, on a Square Base in a Horizontal Plane 36 PROBLEM XI. To draw any Curve in a Horizontal or Vertical Plane 38 PROBLEM XII. To divide a Circle drawn in Perspective into any given Number of Equal Parts 42 PROBLEM XIII. To draw a Square, given in Magnitude, within a larger Square given in Position and Magnitude; the Sides of the two Squares being Parallel 45 PROBLEM XIV. To draw a Truncated Circular Cone, given in Position and Magnitude, the Truncations being in Horizontal Planes, and the Axis of the Cone vertical 47 PROBLEM XV. To draw an Inclined Line, given in Position and Magnitude 50 PROBLEM XVI. To find the Vanishing-Point of a given Inclined Line 53 PROBLEM XVII. To find the Dividing-Points of a given Inclined Line 55 PROBLEM XVIII. To find the Sight-Line of an Inclined Plane in which Two Lines are given in Position 57 PROBLEM XIX. To find the Vanishing-Point of Steepest Lines in an Inclined Plane whose Sight-Line is given 59 PROBLEM XX. To find the Vanishing-Point of Lines perpendicular to the Surface of a given Inclined Plane 61 APPENDIX. I. Practice and Observations on the preceding Problems 69 II. Demonstrations which could not conveniently be included in the Text 99 PREFACE.