It is of fundamental importance in making an investigation of this type that the allowance for fatigue be greater than the physical condition of the worker at the end of the day seems to indicate necessary. It is also fundamental that the results of the investigation be at once incorporated into actual shop practice. If each member of the organization is at once placed under such working conditions that he can enjoy the rest periods along with the high pay that comes from a large product, he will co-operate most fully in the progressive work of fatigue elimination. It is a fundamental rule of scientific management that the rate once set must never be cut. It should also be a fundamental principle of our management that rest periods once established should not be abolished or shortened. Let the error, if error there is, always result to the advantage of the worker, never to that of the employer. If you have not allowed enough rest, make the allowance larger, then reinvestigate. If you have allowed too much rest, let the job stand as one to be given for special merit, and attack some other problem. The result will be an increased co-operation which will more than compensate for the occasional over allowance for fatigue. Summary. Fatigue measurement, as applied to the industries, is a new science. It is being developed through a study of the data of activity. The methods of measurement of activity are motion study, micromotion study, the cyclegraph, the chronocyclegraph, and the penetrating screen. Through the data derived by these, we standardize motion paths, motion habits, and all other motion variables. These enable us to test and classify, select and place, both work and workers, and to eliminate unnecessary fatigue. Through the time element we compare our various data, and finally arrive at results that enable us to standardize work and rest periods. Any errors in length of rest periods must result to the advantage of the worker. CHAPTER VIII MAKING ADJUSTMENTS: HOW PRESENT PRACTICE IS DEVELOPED INTO STANDARD PRACTICE A Concrete Example of Making Adjustments. In order to make plain exactly how changes are made and take place from the condition before analysis, measurement, and synthesis are made to the standard method of doing the work, we shall take a concrete example and consider it from every phase. This concrete example will be the assembly of a braider or machine for manufacturing braid, which is a standard product of the New England Butt Company. With the co-operation of Mr. John G. Aldrich, who has since become president of the company, the problem of assembling a braider was studied, both in the laboratory and in the shop.