Self sharpening pencil

Claim 1

A PENCIL DEVICE COMPRISING: AN ELONGATED, HOLLOW, RELATIVELY THIN WALLED TUBULAR CASING HAVING A FORWARD END, A REARWARD END, AND A PASSAGE EXTENDING AXIALLY THERETHROUGH; AN END MEMBER FRICTIONALLY COUPLED TO SAID REARWARD END OF SAID CASING WITH FREEDOM FOR ROTATIONAL AND LONGITUDINAL SLIDING MOVEMENT RELATIVE THERETO; A CUTTING BLADE FIXED TO AN INTERMEDIATE PORTION OF SAID END MEMBER, SAID BLADE HAVING A CUTTING EDGE EXTENDING LATERALLY OF THE LONGITUDINAL AXIS THEREOF AND POSITIONED AT AN ANGLE SUCH AS TO BE POSITIONABLE IN CUTTING CONTACT WITH AND PROGRESSIVELY CUT AWAY THE REARWARD END EDGE OF SAID CASING UPON ROTATIONAL AND LONGITUDINAL SLIDING MOVEMENT OF SAID END MEMBER AND SAID CASING RELATIVE TO ONE ANOTHER, WHEREBY THE LENGTH OF SAID CASING MAY BE PROGRESSIVELY SHORTENED;