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 just because last year's calendar is of no use after December 31. This assurance of a perennial form instead of one which must be renewed or replaced every year is no small advantage. Figures designating the months for any fiscal year can be printed on the weekly card if desired. In Fig. 212 the figures 8, 9, 10, etc., indicating the months, can be printed on the cards and thus leave to be inserted by hand each year only the short vertical markings indicating the relation of the weeks and the months.

Data of the American Jersey Cattle Club

Fig. 213. Milk Production of a Jersey Cow, Weekly by Pounds

A card only 4 inches wide is ample to permit plotting two curves simultaneously. There is plenty of space to allow for two columns of figures giving data for all points on either curve and yet permit lettering a title along the top of the card. A card only four inches wide is advantageous because it can be used in a standard filing case like that seen in Fig. 217

Fig. 213 shows the weekly curve card used in the records of a dairy farm. The particular curve shown is for a prize Jersey cow which was being very carefully tested in the hope of breaking the world's record for milk production. The milk production each week is indicated here, in pounds, together with the butter-fat analysis taken at various intervals.