Writing instrument

Claim 1

IN A WRITING INSTRUMENT, A BARREL HAVING AN OPEN UPPER END, A LOWER END, AND PROVIDED WITH A PLURALITY OF SPACED WRITING CARTRIDGES SELECTIVELY SLIDABLE THROUGH THE LOWER END OF THE BARREL INTO WRITING POSITION, SAID CARTRIDGES COMPRISING ORGANIC PLASTIC MATERIAL, A SPACER ASSEMBLY WITHIN AND GENERALLY COAXIAL WITH SAID BARREL, SAID ASSEMBLY HAVING PLURALITY OF RADICAL WINGS DIVIDING THE INTERIOR OF THE BARREL INTO AT LEAST THREE CHAMBERS OF SUBSTANTIALLY SIMILAR NON-CIRCULAR CROSS SECTION FOR RECEIVING THE CARTRIDGES, ADJACENT WINGS DEFINING BETWEEN THEM A DIHEDRAL ANGLE, THE REAR OF EACH CARTRIDGE HAVING SURFACES DEFINING A DIHEDRAL ANGLE APPROXIMATELY EQUAL TO THE DIHEDRAL ANGLE DEFINED BY SAID WINGS, SAID CARTRIDGES BEING POSITIONED IN SAID CHAMBERS WITH THE REAR OF THE CARTRIDGES NESTED IN THE ANGLE DEFINED BY SAID WINGS TO MAINTAIN THE CARTRIDGES SUBSTANTIALLY NON-ROTATABLE, THE FRONT OF EACH CARTRIDGE COMPRISING AN ARCUATE SURFACE HAVING RADIUS OF CURVATURE APPROXIMATELY EQUAL TO THE RADIUS OF CURVATURE OF THE INTERIOR OF THE BARREL, SAID SPACER ASSEMBLY INCLUDING RESILIENT MEANS FOR URGING SAID CARTRIDGES AGANST THE INNER SURFACE OF THE BARREL SAID BARREL BEING PROVIDED WITH A PLURALITY OF CIRCUMFERENTIALLY SPACED LONGTIUDINALLY EXTENDING SLOTS THERETHROUGH, AN OUTWARDLY EXTENDING DETENT ON THE FRONT OF EACH CARTRIDGE, SAID DETENT BEING RECEIVED WITHIN ONE OF SAID SLOTS WHEN SAID CARTRIDGE IS IN THE PROJECTED WRITING POSITION TO RELEASABLY LOCK THE CARTRIDGE AGAINST UPWARD MOVEMENT, AN OUTWARDLY EXTENDING PROJECTION ON THE FRONT OF EACH CARTRIDGE AXIALLY ALIGNED WITH THE DETENT THEREON, SAID PROJECTION EXTENDING THROUGH SAID SLOT AND DEFINING MEANS FOR SELECTIVELY MOVING EACH OF THE CARTRIDGES INTO WRITING AND NON-WRITING POSITIONS, EACH OF SAID CARTRIDGES BEING HOLLOW, WRITING FLUID WITHIN THE CARTRIDGES, AND A BALLPOINT WRITING TIP AT THE FORWARD END OF EACH CARTRIDGE, THE HOLLOW OF SAID ORGANIC PLASTIC BODY PORTION BEING DEFINED BY A LONGTITUDINLLY EXTENDING BORE EXTENDING FROM ADJACENT THE WRITING TIP UPWARDLY BEYOND SAID LATERALLY EXTENDING PROJECTION, SAID BOYD PORTION HAVING VENT MEANS THEREIN FOR VENTING SAID BORE TO THE ATMOSPHERE.