The space toward the left-hand side of the cards shown in Fig. 205 is for remarks which may be necessary to explain different fluctuations in the curves. In Fig. 206 full circles along the curve show those weeks in which a full holiday reduces the amount of the payroll. In the month of x4pril there was, for this particular plant, a half-holidaj' on the nineteenth. This is shown by a half circle. At the end of the fiscal year we see in Fig. 206 stars to explain why the curve showed a drop to less than

CURVES FOR THE EXECUTIVE 263

one-half in the normal size of the payroll. The plant was shut down at the end of the fiscal year in order that an inventory might be taken.

The notes at the left-hand side of the card are absolutely essential to explain unusual conditions affecting the curves. In two years after an event, most managers are entirely unable to explain certain peaks or valleys in a curve, though these extreme fluctuations may be due to such events as fires, floods, or strikes. Unless the causes of unusual fluctuations are recorded, the curves would have far less than their possible utility to any new man who must take up the manager's task as his assistant or as his successor. An example of the kind of information which should be noted on the curve-card margin came up in a large public-service company, where the manager was for several minutes unable to explain a very great fluctuation which had affected the earnings of a trolley company some two years before. After careful study to explain the drop in the curve, he finallj^ recalled that this trolley line was in a city where all cars must pass over a drawbridge between two sections of the town.