This chair is of type one, devised for doing work that has always been considered sitting work, either standing or sitting. In this case an ordinary chair has been boosted so that a worker can sit at a work-bench made exactly the right height for standing work. The chair is provided with ball-bearing casters, so that it can be pushed out of the way or pulled into position with little effort. This device helped make it possible to divide each hour into work periods and rest periods; and at the same time into standing and sitting periods,--thus not only eliminating unnecessary fatigue, but providing an efficient means for recovery from necessary fatigue.] [Illustration: FIG. 13 This chair is of type two, devised for doing work that has always been considered standing work, either standing or sitting. By its use, heavy filing can be done with greater ease and with the same speed and efficiency. The chair is inexpensive and easy to construct, and is of such a height as best suits the individual worker.] [Illustration: FIG. 14 Another view of the chair as shown in Fig. 13. The projecting foot-rest on this chair enables a man to push the file as efficiently and more comfortably seated than standing.] Chair No. 2 is devised in order that a kind of work which has always been done standing may be done sitting. The work is heavy filing done at a vise, and the chair is provided with a projecting foot-rest. The work-bench is of such a height that the man may work either standing or sitting. In actual practice the filer works half of the time sitting, and half of the time standing. Chair No. 3 is designed to eliminate vibration of floors that carry much high-speed machinery. An ordinary chair is provided with springs, that relieve the operator of one hundred per cent. of the vibration of the floor. This chair was designed for work at a machine, and the operator is provided with a foot-rest, which rests on felt to kill the vibration. Note also the verandas on two sides of the chair for foot-rests. The fourth type of chair is also a shock absorbing chair, which is more complicated in its construction. The fifth type of chair is designed for school work, and has a rest for the right arm that may be lowered or put in place. The sixth type of chair is a modification of a chair already in use. A chair which was once, perhaps, fairly comfortable has become worn off from years of use. This is rectified by boring holes in four small blocks of wood, and fitting them to the legs of the chair, which brings the chair back to its originally desired height. A well-known Middle West manufacturer used iron piping for the same purpose as the four blocks of wood. This is, in some cases, easier to secure, although not so good for the shop flooring.