 Complete the following phrase:  The first demonstration of the instantaneous transmission of images was made by a German physicist, Ernst Ruhmer, who arranged 25 selenium cells as the picture elements for a television receiver. In late 1909 he successfully demonstrated in Belgium the transmission of simple images over a telephone wire from the Palace of Justice at Brussels to the city of Liege, a distance of . This demonstration was described at the time as the worlds first working model of television apparatus. The limited number of elements meant his device was only capable of representing simple geometric shapes, and the cost was very high; at a price of 15 US45 per selenium cell, he estimated that a 4,000 cell system would cost 60,000 US180,000, and a 10,000 cell mechanism capable of reproducing a scene or event requiring the background of a landscape would cost 150,000 US450,000. Ruhmer expressed the hope that the 1910 Brussels 