A FIRST EXPERIMENT 23 Following these conditions, therefore, the experimenter was first of all conducted on extensive tours through the various shops, and the various types of work were ex plained to him. After six or seven trips of this kind, two types of work, conducted side by side in the same room, were settled on as the most fruitful field for the experi ment. The work chosen was that of inspecting shells before they had been loaded, and gauging them for head thickness. This work was being done in two long, well- lighted rooms, by about 330 girls, two-thirds of whom were engaged in inspection and one-third in gauging. This large number of girls offered the opportunity of conduct ing a sufficiently extensive series of observations, thus meeting the third condition stated above. Most of the girls, at the time, were inspecting the same kind of shells, and this fulfilled the fourth condition; namely, a highly standardized type of work. A further advantage offered by this type of work, and one that was absolutely essential to the success of the experiment, was the fact that it offered a basis for comparing the activity of the various workers. For instance, it was possible, at the end of each day, to find out exactly how many pounds of shells each girl had inspected or gauged during the day as well as to find out how many good shells she had thrown out as a yy scrap . The above might be called the preliminary steps of the experiment. We now come to the details of the experi ment itself. The general purpose of the experiment was, as has been stated, to discover a set of tests which would guide the employment office in selecting new candidates. The more specific purpose, at this stage in the experiment, was to discover a set of tests in which the performance of the