| 摘要 |
A rolling-contact adding and subtracting distance measurer comprising a pair of differently graduated endless tapes driven by unequal size sprocket-pulleys integral with a drive wheel rotatively mounted in a palm-sized case, with a portion of the wheel rim protruding from the bottom of the case; idlers carry the tapes in a flat run past an observation window in the top of the case; anti-tip rollers keep the case aligned with the surface to be measured in a typical embodiment.
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