| 摘要 |
<p>A ball which moves in a zig-zag manner when rolled has a shaft traversing two points at opposite sides of a body, with left and right threads engraved on the shaft and a hollow cylinder slid ably mounted on the shaft. A pin connected to the cylinder slid ably contacts the threads and a weight is attached to the cylinder such that the weight, the pin and the threads co-operate to cause the cylinder to reciprocatingly traverse the shaft as the ball rolls.</p> |
