| US Patent: 28,400 
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| Hollow Auger Pump-Log Hollow Auger
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| Manufacturer: |  | Not known to have been produced |  
 
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| Patent Dates: |  
| Granted: | May 22, 1860 |  USPTO (New site tip)
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                        Jeff Joslin (dm)
 
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| Description: |  | The primary claim has to do with the four cutters which are alternately, and opposingly, inclined in order to divide the chips. Also, each cutter is broken into two planes, further breaking up the chips, with the goal of easing their passage up the spirals. 
For a contrary view, see Wyckoff's patent (53722) of 1866. |  |