Writing instrument

Claim 1

A WRITING INSTRUMENT COMPRISING A TUBULAR BARREL OPEN AT ITS OPPOSITE ENDS, SAID BARREL HAVING A LONGITUDINAL OPENING THERETHROUGH, A WRITIG UNIT SLIDABLY MOUNTED IN SAID BARREL AND HAVING A WRITING POINT AT ITS FORWARD END ADAPTED TO BE PROJECTED AND RETRACTED THROUGH THE FORWARD END OF THE BARREL ON SUCCESSIVE DEPRESSION AND RELEASE OF A PUSH MEANS, SPRING MEANS CONSTANTLY URGING SAID UNIT TOWARD A RETRACTED POSITION WHEREIN SAID WRITING POINT IS CONCEALED WITHIN THE BARREL, AND PUSH MEANS SLIDABLY MOUNTED IN SAID BARREL, SAID PUSH MEANS HAVING A FIRST PORTION PROJECTING THROUGH AN END OF SAID BARREL, AND A SECOND PORTION MOUNTED IN NON-ROTATABLE FASHION WITH RESPECT TO SAID BARREL, A PLURALITY OF CIRCUMFERENTIALLY SPACED INCLINED TEETH IN SAID BARREL, SAID LONGITUDINAL OPENING RECEIVING THE LOWER END OF SAID PUSH MEANS, SAID OPENING BEING RADIALLY ENLARGED AT SPACED CIRCUMFERENTIAL LOCATIONS TO DEFINE LONGITUDINALLY EXTENDING CHANNELS, THE CROSS-SECTIONAL SHAPE OF SAID LONGITUDINAL OPENING, EXCLUSIVE OF SAID CHANNELS, BEING GENERALLY A POLYGON HAVING SUBSTANTIALLY STRAIGHT SIDES, SAID SECOND PORTION OF SAID PUSH MEANS HAVING A CROSS-SECTIONAL POLYGONAL SHAPE TO COOPERATE WITH THE POLYGONAL SHAPE OF THE LONGITUDINAL OPENING TO MAINTAIN SAID SECOND PORTION NON-ROTATABLE, THE SECOND PORTION OF SAID PUSH MEANS, AT CIRCUMFERENTIALLY SPACED LOCATIONS, BEING RADIALLY LARGER THAN THE FIRST PORTION OF THE PUSH MEANS IN LONGITUDINAL ALIGNMENT WITH SAID LOCATIONS TO PROVIDE RADIALLY EXTENDING CIRCUMFERENTIALLY SPACED SHOULDERS BETWEEN SAID FIRST PORTION AND SECOND PORTION SO THAT DURING ASSEMBLY OF THE PUSH MEANS INTO SAID OPENING, IN THE EVENT SAID SHOULDERS ARE LONGITUDINALLY ALIGNE WITH THE INCLINED SURFACE OF SAID TEETH, THE INCLINATION OF SAID TEETH WILL CAUSE ROTATION OF THE PUSH MEANS UNTIL THE SECOND PORTION OF SAID PUSH MEANS IS ROTATAIONALLY ALIGNED WITH THE OPENING TO BE RECEIVED THEREIN.