 Complete the following phrase:  One of the key inventions in the world history of trams was that of the girder rail developed in 1852 by Frenchman Alphonse Loubat. It brought the tram track down to road level, avoiding accidents with pedestrians and other vehicles caused by the standard protruding rail used until then. Inspired by John Stephenson of New York City, it was in Paris that Loubat built the first line of this type, for horse trams, which was inaugurated on 21 November 1853 in connection with the 