Mary's Hospital in Paddington, London, England. In May, 1887, Waller demonstrated his method to many physiologists. In 1888, Waller demonstrated that the contraction of the heart started at the apex of the heart and ended at the base of the heart. Willem Einthoven was among those who took interest in the new method. He would end up improving it in the 1900s. 1887–1889: The Serbian-American engineer Nikola Tesla files patents on a rotating magnetic field based alternating current induction motor and related polyphase AC transmission systems. The patents are licensed by Westinghouse Electric although technical problems and a shortage of cash at the company meant a complete system would not be rolled out until 1893. 1887–1890: Sebastian Ziani de Ferranti of Liverpool, England is hired by the London Electric Supply Corporation to design the Deptford Power Station. Ferranti designed the building, as well as the electrical systems for both generating and distributing alternating current (AC). Among the innovations included in the Station was "the use of 10,000-volt high-tension cable", successfully tested for safety. On its completion in October 1890 it was the first truly modern power station, supplying high-voltage AC power. "Ferranti pioneered the use of Alternating Current for the distribution of electrical power in Europe authoring 176 patents on the alternator, high-tension cables, insulation, circuit breakers, transformers and turbines." 1888: Heinrich Hertz of Hamburg, a city-state of the German Empire, successfully transmits and receives radio waves. He was employed at the time by the Karlsruhe Institute of Technology. Attempting to experimentally prove James Clerk Maxwell' "A dynamical theory of the electromagnetic field" (1864), Hertz "generated electric waves using an electric circuit". Then he detected said waves "with another similar circuit some distance away". Hertz succeeded in proving the existence of electromagnetic waves. But in doing so, he had built basic transmitter and receiver devices. Hertz took this work no further, did not exploit it commercially, and famously did not consider it useful. But it was an important step in the invention of radio. 1888–1890: Isaac Peral of Cartagena, Spain launches his pioneering submarine on September 8, 1888. Created for the Spanish Navy, el Peral was "roughly 71 feet long, with a 9-foot beam and a height of almost 9 feet amidships, with one horizontal and two small vertical propellers, Peral's "cigar," as the workers called it, ... had a periscope, a chemical system to oxygenate the air for a