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| Patents for Derby Bit Co. | |||||
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| Number | Date | Patentee | Title | Type | |
| 155,333 | Sep. 22, 1874 | W.L. Parmelee | Improvement in expansion-bits | adjustable drill bits | |
| 260,497 | Jul. 04, 1882 | W.L. Parmelee | Improvements in Expansion-Bits | adjustable drill bits | |
| 281,920 | Jul. 24, 1883 | W.L. Parmelee | Bit-stock | braces | |