the intersecting strips 32 34 are relatively thick and others are relatively thin as generally illustrated in fig2 other forms of lattice like grids and other dimensions may however be substituted for that described it is to be understood that all of the liquid contact plates in each tier level are interconnected according to the invention in a manner to be described thus at each tier level the liquid contact plates present a substantially integral cooling assembly making reference to fig1 the representative liquid contact plate 20 according to the invention utilizes the molded side bars 24 26 28 and 30 of rectangular cross section to support the molded intersecting strips 32 34 and to thereby form a planar perforate surface for cooling the liquid which drips through the various tiers of the tower side bars 24 26 28 and 30 are each molded with a pair of inwardly protruding locking ribs respectively designated as locking ribs 40a 40b on the inner side surface of side bar 24 locking ribs 42a 42b on the inner side surface of side bar 26 locking ribs 44a 44b on the inner surface of side bar 28 and locking ribs 46a 46b on the inner surface of side bar 30 using locking ribs 40a as an example it will also be noted that the locking rib 40a has a protrusion 41 for.