Shortly before the late war a small volume entitled "The Riddle of the Sands" had a large circulation. It described the adventures of two friends, who, in a small yacht, spent their summer vacation in cruising on the Friesland Coast of Germany, and it gave a graphic account of their discovery of a wonderful network of canals and waterways which had been made through the sands, connecting the ports of Emden, Wilhelmshaven and Cuxhaven. Mysterious craft flitted about, and their own movements were carefully watched. What is this "riddle of the sands" they asked? The war gave the answer. It was a great submarine base for an attack upon England. We in Liverpool have our riddle of the sands, which, although very different in character, has proved equally elusive. It has defied scientific solution, the teaching of hydrodynamics, and has from time to time almost threatened the existence of the port of Liverpool, and with it the prosperity of our manufacturing districts. The approaches to the port have not been maintained (although assisted) by the use of mechanical or scientific means, but by encouraging the natural forces to do the work necessary to maintain the deep water entrances clear and serviceable. There are many now living who remember that the deep water approach to Liverpool was through the Rock Channel only with three feet of water at low water, with dangerous and shifting shoals off the Spencer Spit, and the long lee shore off the West Hoyle Bank. If these conditions had continued the Liverpool of to-day would not have existed. The development of the northern deep water approaches is an interesting study. Liverpool has solved her own "Riddle of the Sands," not by colossal ambitious engineering schemes which might have been fatal, but by patient watchfulness of what nature was doing, or trying to do, and judiciously assisting her efforts. Nature has practically closed the Rock Channel and the old Victoria Channel, and concentrated her forces and opened up the Queen's Channel with over 20 feet of water at low tide in the dredged cut at the Bar, thus making the port open for ordinary vessels during twelve hours out of the twenty-four, and making Liverpool the great port she is--the only deep water port on the West Coast capable of taking such great ships as the "Aquitania" and "Olympic." [Illustration: SS. "Aquitania," 1914] The Riddle of the Sands as it presents itself to us, divides itself into two portions:-- The sands of the upper estuary; The sands of the sea channels; each forming a very interesting and entertaining subject of inquiry. THE RIDDLE OF THE UPPER ESTUARY