We further observe, that the great wave of the German Ocean produces its tides in regular succession, and at stated periods, as it moves from north to south; but the tides of the more inland seas are subject to many irregularities, both in their periodic times, and in the direction of their currents. Let us suppose, then, that we have arrived at the instant of high-water on the shores at the entrance of the Firth of Forth, and that the tidal waters are then moving in a body, and with a certain pressure, towards the higher parts of the Firth , and even affecting the river above the bridge of Stirling. We find, that at the entrance of this estuary, on the days of new and full moon, it is high-water at a quarter past one o’clock; but at Alloa, situate 70 miles above the Bell Rock, it is not high-water till about two hours and a half later. The in-shore tidal waters having to encounter the shelving shores, islands, sunken rocks, and projecting points of land, which lie in their course up the Firth , acquire lateral as well as perpendicular motion, and being thus checked in their progress, are brought sooner to a maximum state than the off-shore stream, which flows in deeper water, and comparatively free of obstruction, till it reaches its ultimate limits; though it gradually diminishes in breadth, till the stream of the _new tide_ gaining strength becomes general; and the central current, formerly running in a contrary direction, at length disappears, and takes the course of the new tide.