Tesla Notes 04: Edison, Direct Current and the Arithmetic of Copper
New York, 1884 to 1887: I work for Edison, dig ditches, and prove on paper that copper grows as the square of the distance and falls as the square of the pressure.
Tesla's New York notebook: why 110 V direct current reached about a mile, the I²R arithmetic of copper, Edison's three-wire saving, and the $50,000 story.
Nikola Tesla
November 5, 2026
24 min
