The site of Eridu, about 20 miles from the Euphrates, stands on the edge of a big depression in the desert. The skill of the Sumerians in building canals is beyond question, and herein lies the answer to the puzzle of an inland seaport. The big sandy depression sixty centuries ago was a lake, and the outlet from the lake was by canal to the Euphrates, and so to the sea. Eridu of old was merely the forerunner of Manchester of to-day, and the ancient people solved the problem of bringing the galleys to their very doors, in the same way that the people of Manchester solved the problem of bringing the steamers into the heart of their city six thousand years later. Solomon spoke truly when he said that under the sun there is nothing new. Mr. Campbell Thomson, who has done fine work in Mesopotamia during the past few years on behalf of the British Museum, was the man who solved the mystery of ancient Eridu, and definitely proved that it never stood on the seashore. His Arabs were digging there, to throw some light on the vexed question of the past, when they came across quantities of shells, just as the kitchen middens of Denmark are marked by the shells of the fish the ancient peoples ate. The shells at Eridu were similarly the sole remains of repasts eaten seventy or eighty centuries ago, perhaps longer. The average man would shovel such debris aside, and take no further notice of it, but Campbell Thomson knew only too well the importance of trifles in reconstituting the past. He put specimens of the shells aside, and brought them to England with his other finds. These shells were submitted to an expert, who was asked to identify them. The expert found that the shells were those of fresh-water mussels. Instantly all the theories of those who asserted that the city once stood on the seashore were refuted. If Eridu actually stood on the seashore, the mussels eaten by these primitive inhabitants would have been salt-water fish. As the shells found were those of fresh-water fish, they revealed that Eridu stood on a lake, which the Sumerians undoubtedly connected up by canal with the Euphrates. In this way did a simple thing like a mussel shell reveal another long-lost secret. About four thousand years ago Eridu was deserted by man, and the encroaching sands have gradually silted up the canal and lake. The fact that human beings ceased to live there so long ago might be considered a disadvantage to those exploring the spot, but actually it has proved a tremendous advantage. Human beings have a habit of destroying the remains of those who go before them. They knock down former habitations and rebuild, using previous materials, until all traces of former peoples are lost.