We have not been able to mention all of the western tool builders. Most of these firms have been established in recent years and are busy building up a market and a reputation. Some of them will take positions of leadership as Warner & Swasey and Lodge & Shipley have done, but this of course requires time. There can be no “conclusion” to the history of a live and growing industry. A few of the present tendencies, however, may be pointed out. One of the most far-reaching influences ever received by tool building came from the introduction of high speed steel through the work of Frederick W. Taylor and his associates. These steels made possible much heavier cuts, and increases in cutting speeds, to two or two and one-half times the previous prevailing practice. Mr. Taylor also made a remarkable investigation of the lathe-planer type of cutting tool. A. L. DeLeeuw and others have studied the milling cutter and twist drill and examined the causes of the failure of cutting edges in action, and the influence of large clearances for chips and coolants. The new cutting steels and these investigations have compelled an extensive redesign of machine tools during the past fifteen years, a process which is still going on as new demands are made upon the tool builders. These years have also witnessed a development of the “station-type” of machine, or one in which there are multiple chucks, indexed from station to station, one position being used for putting in and taking out work while a succession of operations is simultaneously going on at the other stations. In general these are high production machines suitable for long runs of standard work. The multi-spindle automatic bar-stock lathe is an example. One of the latest of these station-type tools is the vertical machine shown in Fig. 56, which performs all the functions of an engine lathe and is in effect five lathes in one machine. Another development of recent years has been the extension of the grinding process, both for the rapid removal of metal and for precision work. This has been made possible by the introduction of new and more active abrasives.