In the matter of influencing the behavior of the curve, the two are of equal importance.

The proper construction of a grid involves more than simply covering a convenient space with cross rulings. As in the matter of general layout, the nature of the doto ond purpose of the presentation must be considered. A grid unsuifed to the doto moy be not only lacking in effectiveness but may actually be misleading. . Grids should be so proportioned as not to distort the facts.

2. Grid proportions should not be rigidly standardized.

3. Grids should be of pleasing proportions.

FREQUENCY Of VERTICAL RULINGS

1. The number of rulings should be sufficient to indicate the frequency of plotting.

2. There should be a sufficient number of rulings to facilitate the reading of time values on the horizontal time-scole.

WEIGHT OF VERTICAL RULINGS

1. Vertical rulings should be of sufficient weight to guide the eye readily to the time-scale designations.

2. The weight of vertical rulings should be varied so as to indicate clearly the nature of the time intervals or the subdivisions of time for which data ore shown.

FREQUENCY OF HORIZONTAL RUUNGS

1. Horizontal rulings should be so drawn as to meet the requirements of their two-fold purpose: To assist in reading values on the vertical scale and to provide a series of horizontal bases of comparison

2. The number of horizontol rulings should vary according to the closeness with which it is desired to read values of the vertical scale. Rulings should not be so frequent as to imply a greater accuracy of the data than actually exists.