| 摘要 |
A top is provided with a conical body having a soft porous parabolic point at the top's conical apex which simultaneously grips and tracks a writing surface over which the top travels. When the top is spun, the point at the apex grips the writing surface and allows the top to travel over the writing surface leaving an ink imprint in its path. During spinning, the top precesses with the rotating angular velocity characteristic of a top spinning down about a fixed point. However, the tip of the top at the conical apex does not remain fixed with respect to the writing surface; rather, the tip travels on its own course over the writing surface as a function both the angle of the tip with respect to the writing surface and the angular spin velocity of the top. As a consequence, the travel of the tip interacts with the forces of top precession to produce a group of characteristic traced spirals on the writing surface. In one embodiment of the invention, provision is made to vertically adjust the tip of the top in elevation with respect to the remaining mass of the top to adjustable vary the resultant spirals. A serendipitous result of the combination is that ink filled writing instrument in the top experiences a complete exhaustion of its contained ink supply before ceasing to write-a condition not experienced by most such pens during there in service life.
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