| 摘要 |
Device comprises an element (1) on which times are marked, such as present times or anniversaries of dates in the past. Such dates are indicated by curves (3,4,6) drawn or marked on the element. Such curves are selected or activated by the shade of an object (8) falling onto the curve, at the instants representing the time at which the anniversary falls. The positions of the curves are calculated from the position in which the object will be placed and the geometry of the earth relative to the sun. As an alternative to using the shadow cast by an object, the light beam produced by a cutout in an object can be used instead. |
