on 11 march 1888, ferraris published his research in a paper to the royal academy of sciences in turin (two months later nikola tesla gained , application filed october 12, 1887. serial number 252,132). these alternators operated by creating systems of alternating currents displaced from one another in phase by definite amounts, and depended on rotating magnetic field for their operation. the resulting source of polyphase power soon found widespread acceptance. the invention of the polyphase alternator is key in the history of electrification, as is the power transformer. these inventions enabled power to be transmitted by wires economically over considerable distances. polyphase power enabled the use of water-power (via hydroelectric generating plants in large dams) in remote places, thereby allowing the mechanical energy of the falling water to be converted to electricity, which then could be fed to an electric motor at any location where mechanical work needed to be done. this versatility sparked the growth of power-transmission network grids on continents around the globe.