Lawn sprinkler with gyratory stem

Claim 1

A LAWN SPRINKLER COMPRISING A BODY ADAPTED TO BE MOUNTED ATOP A WATER SUPPLY RISER, THE BODY HAVING AN UPPER END AND A LOWER END AND AN INSIDE SURFACE DEFINING A CAVITY FORMED THEREIN, THE BODY HAVING AN UPPER END OPENING FOR DISCHARGE OF WATER FROM SAID CAVITY, A STEM ARRANGED LONGITUDINALLY IN THE CAVITY AND EXTENDING UPWARDLY BEYOND SAID DISCHARGE OPENING, MEANS ON THE LOWER END PORTION OF THE STEM ENGAGEABLE WITH SAID BODY FOR PREVENTING REMOVAL OF THE STEM OUT THROUGH SAID DISCHARGE OPENING, THE STEM BEING ROTATABLE ON ITS AXIS AND GYRATABLE AROUND IN THE CAVITY WITH THE AXIS OF THE STEM BEING INCLINED WITH RESPECT TO THE VERTICAL AXIS OF THE CAVITY, A HEAD ON THE UPPER END PORTION OF THE STEM FOR DEFLECTING WATER FROM SAID DISCHARGE OPENING RADIALLY OUTWARD FROM THE STEM, THE BODY HAVING A PLURALITY OF SLITS FORMED IN THE SIDE WALL THEREOF FOR FLOW OF FLUID FROM SAID RISER INTO THE BODY CAVITY, SAID SLITS BEING INCLINED WITH RESPECT TO THE RADII OF THE BODY TO IMPART ROTARY MOTION TO FLUID WITHIN THE BODY THEREBY TO GYRATE THE STEM WITHIN THE BODY, SAID CAVITY AND SAID DISCHARGE OPENING BEING OF LARGER DIAMETER THAN THE OUTSIDE DIAMETER OF SAID STEM, THE TOTAL OF THE SLIT SIZES BEING AT LEAST THREE TIMES GREATER THAN THE DIFFERENCE BETWEEN THE SIZE OF SAID DISCHARGE OPENING AND THE CROSS-SECTIONAL AREA OF THAT PORTION OF SAID STEM WHICH IS DISPOSED IN SAID DISCHARGE OPENING, WHEREBY THE INLET CAPACITY TO SAID CAVITY IS GREATER THAN ITS OUTLET CAPACITY, AND THE SLITS BEING AT LEAST THREE IN NUMBER AND SPACED APART UNIFORMLY AROUND THE SPRINKLER BODY.