We would, therefore, be understood to ascribe this anomaly in the flowing and ebbing of the sea, to the obstruction which the current of its waters meets not only at the surface or margin, but at the bottom, which, from the variety of the soundings of the depths, appears to be as various as the face of the land. A striking proof of this is afforded at the Bell Rock: on the northern side of which there are 11 fathoms, at the distance of about three quarters of a mile; while, on the southern side, and at a similar distance, the water deepens to 35 fathoms; so that a perpendicular section of this rock under water forms a precipitous declivity, such as we are quite accustomed to see on the land. Now, if we apply this irregular conformation of the bottom of the sea, to the production of the in and off shore tides, and conceive that the tidal currents extend their motion to the bottom, it must be evident, that this obstruction presented to the stream will bring the tides to a maximum state sooner on the northern side of the rock, where the water is so much shallower, than on the southern side. This is also agreeable to observation; for, the tides _upon the Bell Rock_ begin to flow and ebb one hour sooner than at the distance of about three quarters of a mile from it on the northern side, and about two hours and a half sooner than at the same distance on the southern side. The marginal current is thus checked by the shallowness of the water, and the projecting points of land; while the central stream, flowing comparatively without obstruction, continues to run till the most inland creeks are supplied with tidal water; and _vice versâ_, it continues its stream outwards, till these waters are again run off. [Sidenote: Progressive times of high-water.] The progressive times of high-water, at intermediate points between the Bell Rock and the port of Alloa in the Firth of Forth, appear to follow the same general law, as the great wave of the German Ocean in its progress from the Orkneys southward. These observations on the tides of the Forth apply equally to the Firth and River of Tay, and indeed to all the tributary streams and arms of the sea which communicate with the German Ocean, according to their local situations and magnitudes. [Sidenote: Tides of the Mediterranean and Baltic Seas.] If due allowance be made for the peculiar situation and circumstances of the Mediterranean and Baltic seas, it is apprehended, from all that we have been able to learn of the operation of the currents at the Strait of Gibraltar, and Sound of the Cattigate, that these seas are supplied and discharged by in and off shore tides or currents, under certain modifications, and making due allowance for local circumstances, in the same manner as on all other parts of the coast.