US Patent: 858,498
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| Ruler
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Patentee:
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| John L. Bartels (exact or similar names) - Chicago, IL |
| Manufacturer: |
| Not known to have been produced |
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Patent Dates:
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| Applied: |
Sep. 07, 1906 |
| Granted: |
Jul. 02, 1907 |
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Ralph Brendler
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Description: |
| This ruler is designed to be marked with different scales on each face, and provides a sliding indicator to show the relationship between them. It is designed for elementary school use, for example to show the relationship between the English and Metric measurments. |
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