| US Patent: 858,913 
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| Drafting Instrument | 
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| Patentee: |  |
 | Robert G. Sauer (exact or similar names) - Louisville, KY |  
 
 
 
 
| Manufacturer: |  | Not known to have been produced |  
 
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| Patent Dates: |  
| Applied: | Jan. 30, 1907 |  
| Granted: | Jul. 02, 1907 |  USPTO (New site tip)
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                        Ralph Brendler
 
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| Description: |  | This is a typical draftsmans T-square, with an extra pair of arms attached at right angles to each other, and to a protractor on the T-square.  The claims say this is particularly handy for perspective drawings. |  |