| US Patent: 243,214 
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| Acoustic telephone | 
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| Patentees: |  
 | Henry J. Colburn (exact or similar names) - Fitchburg, MA |  | Irving W. Colburn (exact or similar names) - Fitchburg, MA |  
 
 
 
 
| Manufacturer: |  | Not known to have been produced |  
 
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| Patent Dates: |  
| Applied: | Apr. 08, 1881 |  
| Granted: | Jun. 21, 1881 |  USPTO (New site tip)
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                        Jeff Joslin
 
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| Description: |  | "This invention relates to improvements in acoustic telephones; and it consists, first, in combination with the vibratory diaphragm of a central button head of which is made concave on its under side, where it rests against the outside of the diaphragm, or against a rubber or other washer or packing interposed between it and the diaphragm, by which arrangement we obtain a true bearing of the said button on the diaphragm, as well as an increased supporting-surface for the said button around the central perforation in the diaphragm. The button has an inwardly-projecting perforated shank, as usual, to which the wire is attached which is led to a corresponding acoustic telephone at the other terminus. In combination with an acoustic telephone we employ a lightning-conductor, which is carried from any suitable part of the ring or case to the ground, so as to establish a proper ground-connection to conduct the lightning to the earth in case it should strike and follow the connecting-wires between the telephones."This patent is of interest because the inventors also made machine tools and woodworking machinery. |  |