Cover for drain tile joints

Claim 1

AN ANTI-CLOGGING WATER PERMEABLE JOINT CONSTRUCTION FOR USE AT THE OPEN JOINTS BETWEEN UNDERGROUND DRAINAGE TILES, INCLUDING IN COMBINATION, A PAIR OF DRAINAGE TILES ARRANGED IN END-TO-END RELATION WITH THEIR ADJACENT ENDS SPACED APART, A SHELL MADE OF A COMPOSITION INCLUDING POLYVINYL CHLORIDE, A PLASTICIZER AND METALLIC COPPER AS SOLUBILIZED COPPER, SAID SHELL BEING PRE-FORMED WITH A SUBSTANTIALLY SEMI-CYLINDRICAL SHAPE CONFORMING CLOSELY TO THE UPPER HALF OF THE OUTER CIRCUMFERENCE OF THE DRAINAGE TILES AND HAVING AN AXIAL LENGTH SUCH THAT SAID SHELL OVERLAPS THE ENDS OF ADJOINING TILES AS WELL AS SPANS THE GAP THEREBETWEEN TO PREVENT BACKFILL FROM CLOGGING THE JOINT, SAID SHELL HAVING AN INTEGRAL RIB PORTION EXTENDING INWARDLY FROM THE AXIAL CENTER OF THE INNER SURFACE THEREOF WITH CONVERGING SIDES FOR WEDGING AND UNIFORMLY SPACING THE ADJOINING TILES APART, SAID RIB PORTION HAVING AN INNER BORE EXTENDING LONGITUDINALLY THEREOF TO PERMIT RESILIENT DEFORMATION THEREOF TO ACCOMODATE AXIAL EXPANSION OF THE TILES, AND A STRAND OF HARD COPPER WIRE PREFORMED WITH A CURVATURE SUBSTANTIALLY EQUAL TO THE MEDIAN DIAMETER OF THE TILES AND HAVING EACH END THEROF DOUBLED BACK SO AS TO BE INSERTABLE WHEN SQUEEZED INTO THE RESPECTIVE ENDS OF SAID BORE AND FRICTIONALLY HELD THEREIN WHEN RELEASED, SAID STRAND OF WIRE BEING SUSPENDED FROM SAID SHELL BY SAID DOUBLED BACK ENDS IN SAID BORE ENDS IN THE LOWER HALF OF THE OPEN JOINT BETWEEN THE TILES TO PROVIDE A SOURCE OF METALLIC COPPER WHICH REACTS WITH SOIL ACIDS TO PRODUCE COPPER SULFATE TO INHIBIT ROOT GROWTH THEREIN WHILE PERMITTING PASSAGE OF LIQUIDS THERETHROUGH.