Edison’s final patent
On this day in 1931, Thomas Edison submitted his last patent, a patent for a device with which you can hold an article to be electroplated.
The first great invention developed by Edison in Menlo Park was the tin foil phonograph. While working to improve the efficiency of a telegraph transmitter, he noted that the tape of the machine gave off a noise resembling spoken words when played at a high speed. This caused him to wonder if he could record a telephone message.



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