distance out to sea as never more to be seen or heard of. This misconception arises from & confusion between the tidal impulse, or tidal wave, and the movement of the water under its influence; two things which are totally distinct from one another. The former passes on never to return again, at the rate of one hundred miles per hour, or much more. While the latter, at the different localities, successively finding itself under the tidal impulse, endeavours to keep along with it in its movement at a rate rarely exceeding ten miles an hour; but soon it is left behind, to fall back again with a retrograde movement to its original position, again to be propelled forward by the succeeding tidal wave. Thus while the tidal impulse is one of translation, the movement of the water (on which the objects are borne) is one of oscillation, and that over no great distance. The truth of this may unfortunately be seen, not merely in the neighbourhood of this town, but in the lower reaches of the Thames below the metropolis, and along the shores of most of our seaside towns; the sewage issuing from those places directly into the tideway, and which was to have been got rid of permanently (so it was fondly asserted) by taking itself out to sea, having preferred to follow the ordinary laws of nature, and to gradually deposit itself along the quieter portions of the adjacent shores. TIDES IN THE IRISH SEA. EQUINOCTIAL NEAP TIDE, MARCH 31ST, 1875. Greenwich Time throughout (Dublin Time being 25m. 21s. behind Greenwich). Datum of Levels, 100ft. below English Ordnance. (Assuming the Mean Sea Level to be uniform, Irish Ordnance is 92ft. 6 in. above Datum.) TIDES IN THE IRISH SEA. EQUINOCTIAL SPRING TIDE, APRIL 8TH, 1875. Greenwich Time throughout (Dublin Time being 25m. 21s. behind Greenwich). Datum of Levels, 100ft. below English Ordnance. (Assuming the Mean Sea Level to be uniform, Irish Ordnance is 92ft. 6 in. above Datum.) 108. 0 8.00 93.10 " N.E. Strong Breeze. 30. 0 106. 2 6.15 92.8 N.E. Strong. 105. 1 6.15 91.11 " N.W. Strong. 29.87 RECORDS OF TIDES IN RIVER MERSEY AT LIVERPOOL, TAKEN BY THE SELF-RECORDING TIDE-GAUGE, AT THE GEORGE'S Datum:-Old Dock Sill (O.D.S.) at Liverpool. LEVELS OF TIDES AT LIVERPOOL, Derived from the Record of the Self-registering Gauge at St. George's Pier, deduced from ten years' observations--1854 to 1863. Datum, Old Dock Sill. Ft. ins. Above datum. An extraordinary high tide, as marked on the Leasowe Lighthouse 25.0 23.9 An extraordinary high tide, 20th of January, 1863 Average high water mark of ordinary spring tides, excluding Average high water mark of ordinary neap tides Lowest high water mark of Mean tide level neap tides Highest low water mark of neap tides Average low water mark of ordinary neap tides Lowest low water mark of neap tides Mean low water level - 19.0 Average low water mark of ordinary spring tides, exclusive of equinoctial tides - 11.7 8.7 5.0 4.1 Below datum. 1.5 8.10 5.6 Average low water mark of spring tides, inclusive of |