ESSENTIAL MACHINES 101 effected by fitting strips of the required thickness round the curves, leaving spaces between the strips about equal to their width to be occupied with sand. Fig. 84 is a group of various pipe patterns, two of which on the left are skeleton structures. The cylindrical portions are represented by discs, Fig. 84.óGroup of Pipe Patterns, including Skeleton Structures leaving spaces between, which are filled with sand at the time of mould- ing. The core prints are treated in the same way. The method is only used for work of fair dimensions, and the larger the patterns are the greater is the economy. These examples are by Messrs. Ernest M. Brown &Co. CHAPTER III Essential Machines It is necessary to use the qualifying adjective, because some machines that are absolutely essential in some shops would be like white elephants in others, where they would be only partially employed. The larger the number of hands, and the more varied the kinds of work done, the more extensive is the selection of machines. Small shops handling specialities cannot afford to neglect the facilities that special machines offer. There is a wealth of labour- saving machinery now available, much of which is of comparatively recent growth, notwithstanding that pattern-work is still mainly that of the handi- craftsman.