Lastly, a knowledge of excavating in all its branches is attended with advantage. In the term " excavating" a far greater variety of work is comprised than appears upon the face of it at first sight. It means far more than digging or hollowing out a pit, as for a well or a trench, or for the foundation of a wall. It embraces these, it is true, but it also implies a knowledge of the manufacture if we may use the word of concrete, and the purposes to which it is put, of making garden walks and paths, and of leveling, so far as it may be applied to the construction of drains for carrying off the surplus water from the soil of the garden, or even from a stable or pigsty, and the laying of drain-pipes for this purpose. It also gathers within its wide embrace a knowledge of the method of making tar paving and burning clay into ballast processes which will often be found extremely useful in the garden.