Apparatus for producing perspective drawings from plan view and elevation

摘要

773,932. Perspective drawing-apparatus. FORSTER, F. Aug. 16, 1955 [Aug. 20, 1954], No. 23547/55. Class 97(3) ' Apparatus for producing perspective drawings from a plan view and an eleva tion comprises a fixed column 1 and a column 5 movable over the plan view at G, the latter column carrying a swivel joint in which a rod 4 is slidable through a point P vertically above a selected point'in the plan and which is adjustable in height to correspond to the position of the point in the elevation drawing carried for example on the drum 28 and as indicated by a pointer 27, the other end of the rod being carried in a swivel joint 3 supported by the column 1 and coincident with the centre C of the perspective projection through which a light beam is projected in the direction of the rod 2 td indicate the position PSP1/SP of the selected point in the perspective view. In the form shown the joint 3 is carried on an arm 2 adjustable in 'height on the column 1. The joint supports a nozzle-like end of a casing 7 which contains a lens for projecting an image of a graticule and a lamp and condenser for illuminating the graticule. The graticule is adjustable for focusing by a knurled ring 19. The lamp is laterally adjustable by screws 24. The light beam may be projected directly on to the perspective drawing, being upright, or may be reflected downwardly from a mirror 8, angularly adjustable about the axis of the arm 2, on to the drawing at Z the plane of which mav be angularly adjustable about a hinge 9. The position of the projected point may be recorded photographically; the mirror 8 being at the apex of a light tight enclosure. The base 30 for the column 5 is convex in cross-section and chromium plated to assist sliding. It carries a glass plate or lens 31 with a graticule, for selecting a point in the plan, directly below the point P. The base may be transparent.