It is difficult to define accurately the boundaries of a town or the worst smoke-infested areas, as far as tree and shrub growth is concerned. In London, for instance, certain trees and shrubs which positively refuse to live in the heart of the city do fairly well in the suburbs, while still further out, where the atmosphere is comparatively pure, they may thrive in quite a satisfactory way. These thriving and non-thriving areas are sometimes very sharply defined, and this has given rise to a false idea regarding certain trees and shrubs that will rarely succeed in the more smoky parts when compared with the same species which are found to do well in the outer suburbs. High-lying and fairly open parts of a town are also far more conducive to plant growth generally than those that are close and confined. In town planting there is, however, no necessity for the almost monotonous repetition of such trees as the Plane and Lime, or amongst shrubs, of the Privet and Lilac, for there are many others that will do almost equally well, and that are quite as ornamental. Probably the fact that such are not well known would form an excuse for their absence, and it is to be hoped that at least one object to be accomplished by the writing of this book will be a greater interest in, and wider knowledge of, the various species of trees, shrubs, and plants generally that from long experience have been found suitable for planting in the town garden. =Preparation of the Ground.=—Generally speaking, the materials with which roadways are made are not only unsuitable for tree cultivation, but positively destructive to vegetation of almost every description. This also applies to our squares, terraces, and open grounds around houses, the soil of which is little other than refuse building materials, and mainly composed of broken bricks and stones, gravel, old mortar, iron, wood and shavings. In such a medium it is perfectly useless to look for that healthy and vigorous growth which is so essential in street trees, that are still further handicapped by having to do battle above ground with the impurities of a town atmosphere.