About fifteen miles farther on, we passed the bluff promontory Saint Abb's Head, and soon afterwards arrived off Berwick, which, I need hardly say, stands at the mouth of the Tweed, the river dividing England from Scotland.  So close does the railway run to the cliffs, that we could hear the trains passing as clearly as if we were on shore, and could see them shooting by at a speed which made us jealous.  As the wind was fair, we did not put into the Tweed, but stood close enough to Berwick to have a cursory view of it.  As all the world knows, Berwick is not within any county, for although really in Berwickshire, it belongs to England.  It is a county in itself.  A portion is still surrounded by walls erected in the time of Elizabeth; and it is defended by several bastions, with batteries commanding the entrance to the harbour.  We could see the remains of an ancient castle, which is now a heap of ruins, but above it stands the Bell Tower, still almost perfect. A number of vessels passed in and out of the harbour while we were off it, showing that the place has a good deal of trade.  As we looked through our glasses, we saw a number of churches and public buildings. A long stone pier runs out on the north side of the Tweed, with a lighthouse at its end.