| 摘要 |
A device including a housing having pulleys at opposite ends over which a plurality of belts extend being exposed along their substantial length on the top side. A slider having an opening extending transversely of said belts is movable over the belts. Chronological information is provided on the belts and may be viewed over a substantial period of time through the top of the housing or for one unit of time in the viewing opening in the slider. One of the belts is provided with projection measuring indicia and is movable with the slider to measure into the future and into the past relative to the point of time registering in the viewing opening in the slider. Provision is made for positioning a belt outside of the housing so that belt substitution may be readily achieved. A clamping means is provided on the slider for engaging all the belts to move them with the slider to expose information on the bottom side of the belts.
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