Synthesized answer
The provided passages do not contain enough information to answer what evidence the author provides. The only passage available is a title and page number for a work by Samuel Thomas von Soemmerring [26]. This passage does not include any content from the book that would detail the author's evidence.
Synthesized from the book passages below. Chat with the book on Feynman for follow-up.
From the book
Title: “Der” elektrische Telegraph als deutsche Erfindung Samuel Thomas von Soemmerring's by Samuel Thomas “von” Sömmerring Pages: 26