Southampton. - August 22. This town is wonderfully improved, and increased in size, since we last saw it, when on a walking excursion through the New Forest and the Isle of Wight, in 1807. The elm tree avenue, forming the London approach to the town, has been extended by planting young trees on both sides of the road: but, considering the richness of the corporation, we think they might have formed prepared and manured pits of soil for each tree, and surrounded each by a cradle fence. Instead of this, the trees have been planted in the common soil of the heath or waste, without any stirring or preparation of the soil; and they are only protected by a small hillock of earth heaped up round the root of each tree, and by tying thorns round each stem. Where economy is the great object, this may be allowable, since trees even so planted are better than no trees at all; but here we cannot but consider it as highly discreditable to the town.