In this compact 1893 address - delivered first at the Franklin Institute in Philadelphia, then at the National Electric Light Association in St. Louis - Nikola Tesla walks through his experiments with high-frequency currents, electromagnetic wave behavior, and the nature of light itself.

The lecture captures a pivotal moment in electrical science, when the principles behind transmission, illumination, and high-voltage phenomena were still being worked out in real time before live audiences.

As a primary-source document, it offers grounding in the foundational physics that underpin the electrical infrastructure and safety questions still relevant today.