| 摘要 |
Each post (1) inserted in the ground contains one or more vertical grooves, in which the ends of planks (2) are inserted. One vertical edge of each plank is radiused (3) at the top end and the opposite one at the bottom end (4). Thus on turning the plank from the inclined position into the horizontal one it can be inserted in the grooves of two adjacent posts. The planks can be of tapering cross-section, with one visible surface vertical and the other inclined, typically at 10 degrees to the vertical. The planks can be roughly 20 and 40 mm. thick at their top and bottom edges respectively.
|
