Abstract: A method for constructing underground garage parking units comprises a step of excavating two parallel trenches into which are subsequently sunk preformed reinforced concrete frames each composed of two vertical pillars with an "H"-shaped cross-section and upper and lower horizontal connecting beams disposed between them. The vertical grooves forming the "H" sections being opposed and constituting a guide for the insertion of a plurality of sheet piles so as to form continuous retaining walls in said trenches. The lower of the plurality of sheet piles being subsequently removable with a sideways movement, after excavation of a corridor by removal of the earth between said two walls, for insertion of prefabricated garages at an oblique or right angle into the vertical portions of earth thus uncovered.

Abstract: A container system for a transparency projector is mounted for movement on a guide attached vertically to a wall. The container has an aperture through which projection may be carried out, and further apertures for cooling and electrical connections. The container can be attached to the guide at the required vertical position by means of a screw knob.