Interlocking blocks and construction system comprising said blocks

Claim 1

A building block of integral monolithic construction comprising: (a) two identical sidewalls of rectangular perimeter, each having (1) an interior surface, (2) a flat exterior surface, (3) a flat straight upper abutment edge surface which spans the distance between said interior and exterior surfaces, (4) a lower edge disposed below the corresponding upper abutment edge and parallel thereto in spanning relationship between said interior and exterior surfaces and having at least two steps, the first of said steps being a flat straight abutment surface contiguous to said interior surface, the second of said steps extending between said first step and said exterior surface, and positioned closer to said upper abutment edge than said first step, and (5) first and second vertical edge surfaces of flat straight configuration perpendicularly disposed between said interior and exterior surfaces, the corresponding several edge surfaces of the two sidewalls being in coplanar alignment, and (b) first and second transverse walls located adjacent said first and second vertical edge surfaces, respectively, and disposed between the facing interior surfaces of said sidewalls in perpendicular spanning relationship therewith, each transverse wall being of substantially rectangular perimeter and bounded by a flat exterior abutment surface, an interior surface, and upper and lower edge surfaces perpendicularly disposed between interior and exterior surfaces of the transverse wall, the lower edge surfaces of said transverse walls being disposed below the lower edge surfaces of said sidewalls, the upper edge surfaces of said transverse walls being disposed below the upper edge surfaces of said sidewalls, the positioning of said first transverse wall being such that its exterior abutment surface is located forwardly of said first vertical edge surfaces, and the positioning of said second transverse wall being such that its exterior abutment surface is inwardly displaced from said second vertical edge surfaces in the direction of said first transverse wall, whereby (c) the lower extremities of the transverse walls of the building block make snug interlocking contact with the interior surfaces of the sidewalls of an underlying building block of the same construction, and (d) when placed end to end, the first transverse wall of a building block partially enters the interior space between the sidewalls of a horizontally adjacent building block, interlocking therewith and causing the flat exterior abutment surface of the first transverse wall of one building block to contact the flat exterior abutment surface of the second transverse wall of the next horizontally adjacent building block, (e) said interactive abutment of the building block with identical underlying and horizontally adjacent building blocks causing formation of horizontal and vertical troughs, respectively.