Abstract: For use in a window area of a building, an assembly comprises several generally rectangular translucent building blocks each containing a transparent liquid and an oblique reflecting/refracting surface in contact with the liquid, for pleasing visual effect. The oblique surface intersects, or if produced would intersect, a plane face of the block along a line parallel to one of the rectangular axes.

Abstract: A hollow building block of transparent material comprises four perpendicular walls defining a rectangle, and a partition wall extending obliquely with respect to a plane at right angles to said perpendicular walls, said partition wall forming a boundary of a hollow space within said building block for containing liquid and the arrangement being such that when said hollow space is partially filled with a transparent liquid, light incident upon one of said perpendicular walls of the block can be reflected through said block by total internal reflection at a portion of said oblique wall immersed in said liquid.