Even here at his father's home where he came for rest and peace, Alexander Graham Bell continued to ponder the elusive secret of voice transmission; and it was here, on 26 July 1874, that insight finally came and the fundamental principle of the telephone was conceived. Here also, on 3 and 4 August, 1876, Bell made public demonstrations of his now patented invention, culminating in the world's first long distance call, to Paris, 13 kilometres away, on 10 August.