In this monograph several descendants from the aboriginal tree-bridge are studied briefly, and I refer you to the Index. Some varied English specimens are given in Francis Stone’s “Norfolk Bridges”; and from Don Antonio de Ulloa (1716-1795) we can learn how wooden bridges have long been made in the mountainous parts of South America. They “consist of only four long beams laid close together over a precipice,” and they “form a path about a yard and a half in breadth, being just wide enough for a man to pass over on horseback.” Here the beams have a flat surface, and lie together like boards on a floor. It is primitive handicraft of a low sort, for the beams would carry a much wider footway. VI SOME TYPICAL TIMBER BRIDGES As there is no room here for a pedigree of timber bridges, let us choose a few examples which are particularly famous in history. It will be enough if we take three: (1) a prehistoric lake-village, (2) the Pons Sublicius of the Romans, and (3) the wonderful work done in the eighteenth century by two Swiss carpenters, the brothers Grubenmann. Lake and marsh villages were the highest form of prehistoric bridge-building; their thronged platforms, dotted with round huts, not only put a defence of water between home life and prowling foes, but heralded all the housed bridges that the world has seen during its periods of written history. Whether we study Old London Bridge, or the criss-cross bridges with frail shops in Kashmír (p. 71), or the booth-bridges of China (p. 210 _note_), or the roofed timber bridges of Switzerland (p. 291), we are concerned with a pedigree that starts out from the first Neolithic lake-dwellings. But the later stone period, known as Neolithic, is not very old. Between it and ourselves there is a span of about nine thousand years, or a few thousand years more.[46] But British lake-dwellings are attributed to a time still later, the Bronze Age, whose date in the British Isles may be fixed tentatively at from 1200 to 1400 B.C.[47] Further, as pit-dwellings lasted to the days of Tacitus among some Germanic tribes,[48] so a British lake-village here and there defied progress till the coming of the Romans. There was one at Glastonbury, and its “Late Celtic” routine of life has been studied carefully from its remains.