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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1905 Excerpt:... be seen along the water fronts of New York wherever the sewers fail to discharge into an active current, a condition of affairs which has caused considerable annoyance and led to the removal of many sewer outfalls to the outer, ends of the piers. Observations begun in 1858 show that there is sometimes a layer of distinctly salt water beneath the brackish water in the Hudson for many miles above New York. Some persons believe that there are pockets and potholes in the bottom of the channel in which salt water and sewage accumulate, until a heavy rainfall causes a rush of water down the Hudson which clears them out. This deep current is called the "underrun." The underrun of salt water may be and usually is quite independent of the surface currents. In fact it is often directly opposed to them; there are often two distinctly opposite currents one above the other, flowing at the same time. At a gauging station established by the United States Government in 1858, between Bedloe's, now Liberty, Island arid Governor's Island, the velocity of the underrun moving up the river was found to exceed the velocity of the surface current moving toward the sea. The daily progress of the underrun was 21 miles, at a depth of 68 feet. It is obvious from this and from the fact that the surface water becomes more and more salt at points up the Hudson during dry weather, that the net result of the backward and forward movement of the tides may sometimes be to carry such elements of sewage as are not assimilated up the river, and not out to sea, as is commonly supposed. The following extract from the report of Prof. Henry Mitchell, contained in Appendix 15 of the report of the United States Coast and Geodetic Survey for 1887, p. 308, gives the opinion of the Government...