"The rapid progress of electric lighting in the 1880s, created a demand for practical and reliable measuring instruments. " pagina 373
"The first practical AC motors were developed by Nicola Tesla in 1888. He was born in Austria-Hungary but in 1884 emigrated to the USA where he spent most of his life. He worked for a time for Edison, the leading exponent of DC systems in the USA, then joined Westinghouse, the leading AC man. In his machines Tesla made use of the fact, discovered by Arago in 1824, that a piece of magnetic material free to turn will follow a rotating magnetic field. He created a rotating magnetic field by using two coils energized from supplies that were in synchronism but not in phase. "
pagina 383
"Wilhelm Röntgen, a German, experimenting with a tube invented by W. Crookes in 1878, discovered in 1895 what he called X-ray (X standing for the unknown, as in algebra). A current passed through the Crookes tube caused a piece of paper coated with barium platinocyanide to fluoresce. Röntgen soon started using photographic plates in his experiments, and in 1895 the first Xray of a human hand was made, clearly showing the underlying bone structure; a year later, the first X-ray of a human skull was made. Thus, before the turn of the century, the means to generate and detect a large portion of the electromagnetic spectrum had been found, even if not well understood" pagine 725/726
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