Abstract: A building panel for use in walls of roofs the panel being formed from a sheet of material the sheet being rectangular and made up of four portions the surfaces of each of which are in the form of a hyperbolic paraboloid, the edges of the portions meeting on transverse axes of the panel, corners of said portions meeting at a central point displaced from a plane containing the periphery of the panel. The panel being capable of acting as both the covering and a structural member spanning between frames of a structure thus avoiding the necessity for using pylons, the invention also consists in the use of such panels in a building structure.

Abstract: A method of constructing and erecting a post-tensioned steel frame structure consisting in:1. Constructing on the ground a center span of the structure to each end of which are hingedly connected column structures;2. Post-tensioning the center span by means of a cable to bring the span to a desired shape; and3. Post-tensioning cables connected between each said column structure and the center span to produce relative rotational movement between the column structures and the center span about the hinge joints to raise the column structures from a substantially horizontal to a substantially vertical position thereby elevating the center span to its final position.

Abstract: A hydraulic jack having a piston and a cylinder in which the piston has at its head a cavity the dimensions of the cavity and the constructional materials of the cylinder and the piston being selected so that hydraulic pressure applied within the cylinder acts to deform the cylinder wall and the parts of the piston defining the cavity in such a manner that, over the normal rate of operating pressures of the jack the clearance between the piston and the cylinder remains within the capacity of the sealing means arranged between the piston and the cylinder to provide an effective seal.