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 *fully watched there are certain to be in every herd cows whose milk production is far below the average. Individual records of each cow are now being kept regularly by up-to-date dairies, and any cow that fails to give a definite minimum of milk with a definite per cent of butter-fat is sent to the butcher. Curve cards are a convenient means of recording the output of each cow in such form that instant comparison between cows is possible.

Fig. 215. Actual Cost per Ton at a Factory for Five Years by Months. The Fine Line Shows Monthly a Moving Average of the Cost for the Preceding Twelve Months

The arrow shows it is desired that the cost should go down. Since there is no hope of getting the cost below 50 cents per ton, the zero line is not shown and the bottom of the chart has a wavy line to indicate that the bottom is not at zero

In Fig. 214 a record for one cow for a period of five years is shown on a 4-by-12-inch card. As the card 12 inches long is necessary for weekly records, a card of the same size can be used conveniently to show five years by months instead of using five separate 4-by-6-inch cards, one for each year. In Fig. 214, the figures at the top of the card show the