National Geographic : 1898 Sep
ATLANTIC ESTUARINE TIDES Hudson River Tides 0 I II III IV V VI VII VIII IX X XI H. W. interval from Sandy Hook. 0 19 15 19% 21% 10% 11% 9% 109%9% 8 H. W. advance in last hour (miles). 4.6 4.2 3.6 3.3 3.3 3.3 3.4 3.2 3.0 2.9 2.4 ..... .... Mean tide range (feet). h.m.h.m.h.m.h.n. h. m. h. m. h.m.h.m.h.m.h.m.h.m . m. 67549549544547543527519457452442.........Durationofrise. 61863663664163864265876728733743.........Durationoffall. The two curves below, which I owe to the courtesy of the Superintendent of the Coast Survey, show 48 hours of continuous observation at Albany and Sandy Hook. Both are on the same scale, and they well illustrate the extremes met in a river. The Albany tide, figure A, shows the characteristic steep front of waves that have traveled far in shallow water. The Hudson gets aid in its struggle with coastwise sands at Sandy Hook from the constant westward flow of water from Long Island sound through East river and out to sea.* In closing this examination of estuary tides it appears that they vary from the type in our area only as their estuaries vary from the type of a river valley, narrow above and wide below, partly drowned in the sea. The commonest modification of this geographic type on the Atlantic coast results from the tendency of coastwise sands to close the bay mouths. This agency is evi dent at the mouths of the Hudson and Delaware; it gives the Chesapeake tides of a river type and encloses the mouths of the drowned valleys further south, forming the sounds in which lunar tides are less significant than the effects of prevailing winds. * H. Mitchell: Ann. Rep, U. S. Coast Survey, 1886.