723 HYDROGRAPHIC MANUAL PaGE 664 



723. Lettering 



The lettering oii a smooth sheet should be bold rather than the reverse. Extremely . 

 small letters and numerals should be avoided unless lack of space renders a small size 

 absolutely necessary. Thin ink should be avoided. Unless ink of sufficient body is 

 used, the central part of the inked line frequently thins out, particularly where a 

 mechanical lettering set is used. This results in a poor appearance and makes satis- 

 factory photography of the smooth sheet impossible. Each inked line, whether in black 

 or color, should present a solid uniform appearance throughout. 



It should be noted that, in general, any number appearing in the water area of 

 the smooth sheet should be in slanting numerals, except of course the soundings and 

 position numbers, which are vertical (see 7825 and 7843). 

 Periods shall not be used in the water area (see 781). 



7231. Mechanical Lettering Sets 



Unless the draftsman is particularly skilled in lettering, it is preferable that a 

 mechanical lettering set be used, where practicable. There are several types of these 

 on the market (see 4834). For most small lettering the pen sizes recommended by 

 the manufacturer of the Leroy sets produce too heavy a letter. The preferable size 

 for smaller lettering, such as station names, is "No. 00." 



724. Selection of Pencils 



Although individual preferences vary somewhat, the experienced draftsman know- 

 with which make and grade of pencil he can obtain the best results for any given require- 

 ments. All makes of drawing pencils listed in the General Schedule of Supplies, the 

 standard list of materials contracted for by the Government, can be considered of high 

 grade and of comparable quality, although tests have shown that a variation of approx- 

 imately one grade may be found in the hardness of one make as compared with another. 

 Gradations of any one make, however, can be depended upon to be consistent. Before 

 being listed in the General Schedule of Supplies, drawing pencils are rigidly tested to 

 determine whether they comply with the specifications. The leads in most pencils 

 are made by the same process. Of those listed in the General Schedule in 1942 the 

 Van Dyke Microtomic Graphite is believed to smudge the least and the Koh-i-noor 

 and Turquoise pencil leads are thought to average slightly harder for the same grade 

 than other -makes. It is also the belief of some draftsmen that the Koh-i-noor leads 

 are, on the average, of a more uniform quality. 



For most pencil work on a smooth sheet, pencils of a grade no harder than 3H or 

 4H should be used, except for the construction of projections and the plotting of control 

 stations by dms. and dps. (see 7411). For these a much harder pencil should be used, 

 extreme care being required to prevent damage to the surface of the paper. On 

 a humid day when the paper is likely to be damp and easily indented, a pencil one 

 grade softer should be used than is customary for the same purpose on a dry day. 



Under no circumstances should a hard chisel-edged .pencil be used to draw the 

 connecting lines between positions on the smooth sheet, because this may result in 

 ruptiiring the paper at the most critical place, that is, along the line of soundings. 

 Furthermore, the indentation formed makes inking the soundings extremely difficult, 

 because the pen catches in the indentation. A pencil no harder than 4H, sharpened 

 to a point, not a chisel edge, should be used for this purpose. 



