When curves are to be printed, do not show any more coordinate lines than necessary for the data and to guide the eye. Lines l^:;i^-inch apart are sufficient to guide the eye.

A FEW CAUTIONS 363

21. Make curves with much broader lines than the co-ordinate ruhng so that the curves may be clearly distinguished from the background.

22. Whenever possible have a vertical line of the co-ordinate ruling for each point plotted on a curve so that the vertical lines may show the frequency of the data observations.

23. If there are not too many curves drawn in one field it is desirable to show at the top of the chart the figures representing the value of each point plotted in a curve.

24. When figures are given at the top of a chart for each point in a curve, have the figures added if possible to show yearly totals or other totals which may be useful in reading.

25. Make the title of a chart so complete and so clear that misinterpretation will be impossible.

The American Society of Mechanical Engineers has invited about fifteen of the societies of national scope in America to co-operate in a Joint Committee on Standards for Graphic Presentation. The societies included are largely societies whose members have extensive use for graphic presentation in their daily work. One member from each society will be on this committee. It is hoped that the committee will be able to recommend a small number of brief and simple rules which may be used as a sort of grammar by persons who have graphic presentations to prepare and to interpret. Reports from this joint committee should be watched for so that any rules which may be agreed upon may be put into effect as soon as possible.