Air distribution devices and grilles

Claim 1

AN AIR DISTRIBUTION GRILLE COMPRISING A RECTANGULAR GRILLE MADE UP OF A SERIES OF SPACED, METAL GRILLE BARS EXTENDING PARALLEL TO EACH OTHER THE LENGTH OF SAID GRILLE AND DEFINING THEREBETWEEN PARALLEL AIR PASSAGES THROUGH SAID GRILLE, SAID GRILLE BARS HAVING NEAR EACH END THEREOF A CYLINDRICAL HOLE THEREIN WHICH IS ALIGNED WITH, AND OF EQUAL SIZE TO, THE OTHERS OF SAID HOLES IN EACH RESPECTIVE END OF SAID BARS TO FORM A FIRST AND SECOND SERIES OF ALIGNED HOLES THROUGH SAID BARS, A FIRST, THIN-WALLED TUBE OF AN OUTER DIAMETER SLIGHTLY LESS THAN THE DIAMETERS OF SAID FIRST SERIES OF ALIGNED HOLES EXTENDING THROUGH SAID FIRST SERIES OF HOLES, A SECOND TUBE OF AN OUTER DIAMETER SLIGHTLY LESS THAN THE DIAMETERS OF SAID SECOND SERIES OF ALIGNED HOLES EXTENDING THROUGH SAID SECOND SERIES OF HOLES, THE INSIDE WALL OF EACH OF SAID TUBES BEING FLUTED LONGITUDINALLY WITH A PLURALITY OF CIRCUMFERENTIALLY SPACED GROOVES OF SMALL BUT SUFFICIENT MAGNITUDE TO DISTORT THE OUTER SURFACE OF EACH TUBE INTO A PLURALITY OF CIRCUMFERENTIALLY SPACED RIBS WHICH PRESS AGAINST THE CYLINDRICAL WALLS OF SAID CYLINDRICAL HOLES AND FIXEDLY HOLD SAID BARS ON SAID TUBES, AND A RECTANGULAR FRAME HAVING A FRONT FACE AND REARWARDLY-EXTENDING SIDES DEFINING AN AIR PASSAGE CONTAINING SAID GRILLE, SAID REARWARDLY-EXTENDING SIDES HAVING APERTURES THEREIN ALIGNED WITH THE OPEN ENDS OF SAID TUBES, AND A PIN EXTENDING THROUGH EACH APERTURE AND WEDGED IN THE RESPECTIVE OPEN END OF SAID TUBES TO FIXEDLY MOUNT SAID GRILLE IN SAID FRAME.