Sir Ambrose Fleming, later the inventor of the thermionic valve, gave these Christmas Lectures for a young audience at the Royal Institution. He shows how waves form and travel in water, how sound waves carry through air, how resonance builds from small timed pushes, and how electric waves in the ether make wireless telegraphy possible, with many experiments described step by step.
A clear introduction to wave physics from the dawn of radio, for curious readers of any age. Download the free EPUB.