drawings and maps are much more easily read and nnore 

 orderly in appearance than are labels placed at various 

 angles. 



Never letter the figure legend directly on the illustra- 

 tion. 



Symbols.— Use symbols only when they are necessary to an 

 understanding of the figure. Do not use synnbols that become 

 illegible when printed, such as partly filled circles or 

 squares (© <J H a), circles or squares with crosses or 

 dots in them ( ^ ® XI S ), or crosses or X's used alone 

 (+ X ) . If only two symbols are needed use circles, open 

 and solid. If additional symbols are required, use squares, 

 open and solid, and triangles, open and solid, in that order. 



Symbols must be large enough on the original drawing 

 to reproduce properly, A good rule in deciding how large 

 a symbol should be is to make its diameter about the same 

 as the height of the medium- sized letters in the graph. 



UNIFORMITY 



Uniformity within a series of charts or graphs is highly 

 desirable, since it improves the general tone of the report. 

 While a lack of uniformity may not siffect the legibility of 

 the drawings, it does give an impression of careless, un- 

 professional work. On the other hand, real confusion could 

 result fronn inconsistent use of synnbols or patterns in a 

 ■cries of curves for the same variable. 



Lack of uniformity sometimes results from the illustra- 

 tions being prepared by different draftsmen or at different 

 times, but a little forethought can avoid inconsistency in their 

 design. After the first illustration in the series has been 

 suitably planned, you should maJ^e certain that all other 

 drawings in the series harmonize with it. Uniform illustra- 

 tions permit the same reduction, promote consistency in 

 lettering, lines, and other features of the drawings, simplify 

 makeup, and result in an improved format. 



Follow the accepted abbreviations, spelling, and use of 

 numerals given in the Government Printing Office Style 

 Manual to avoid variations between text and illustrations 

 and even among the illustrations. If you are preparing 

 illustrations for outside journals, follow their style; but 

 if you decide later to use the same illustrations in a Serv- 

 ice publication, nnodify thenn to nneet Service specifications. 



CONFORMITY WITH GRAPHIC STANDARDS 



Since the graphic presentation of data is an important 

 part of most technical papers, the illustrations submitted 



14 



