DETAILING GENERAL INSTRUCTIONS Lettering. In order that the drawing may give the necessary information and that no mistakes should occur in the reading of the drawing by the shopmen or others, it is necessary that the letters and dimensions upon the drawing be made so that they are exceed ingly clear. In order to save time in lettering, an alphabet should be used that can be made quickly and easily. The alphabet which is known as the straight-line alphabet fulfills these conditions. It is made by one of the characters or by a combination of the acters shown in Fig. 28. A study of Fig. 29 will show that the general scheme of this system consists of the oval and the straight line.
The slant at which these letters are made is a very important factor in a drawing, the proper slant being 3 in 8, as shown in Fig. 30. Even a slight in crease, however, will give one the im pression that the letters lean too far forward and it will spoil the appearance of a drawing otherwise good.
The height of the lower part of the letter should be equal to two-thirds or more of the total height. Figures should be of the same height as the capital letters. The total height of the small letters should not be less than one-tenth of an inch. This makes the capitals three-twentieths of an inch high, not less. The reason for adopting this height of letters is in order that, if necessary, ordi nary tracings may be reduced for publication and the letters will then show up clearly. Fig. 31 shows the complete alphabet and the numerals from 1 to 0, also several fractions. The fractions should never be made less than one-tenth of an inch in height for each of the members, and the dividing line should be horizontal, never slanting. Fig. 31 also shows by means of small arrows the direction the stroke should take when making the different letters and figures.
There is a tendency to make several of the letters and figures as shown in Fig. 32. This tendency should be carefully avoided, special attention being called to the turned-up ends of the members of different characters. Care should be taken not to get the upper
part of the s and the 8 larger than the lower part. If this is done or if the two parts are made equal the upper will appear to be much larger and these acters will look out of tion.
.The capital letters S, 0, E, F, P, and R, and the figures 2 and 5, present some difficulties. These characters arc shown in Fig. 33, and may briefly be commented on as follows: Letter S. The letter S should begin at the point 1 slightly inside of the circumscribed parallelogram. The line should then be tangent to the top and should come slightly inside of the further side at point 2. It should then cross the center line above the middle height at the point 3 and be tangent at point 4 and point 5 as indicated.
Letter C. The letter CI should start at the right side of the parallelogram and be tangent to the top, left side, and bottom as well as the right-hand side where it extends upward to a height of one-half of its total height before the horizontal line, which should eitend one-half of the distance across the letter, is drawn.
Letter E. The letter E presents no difficulties other than a central horizontal line should extend about two-thirds of the distance across the letter and should he at an elevation of two-thirds the height.
Letter F. The letter i; is but a part of the letter E as indicated.
Letters P and R. P and R are constructed on the same general principle. The upper part of both letters should be at least one-ELlf or more of the total height, and in the case of R the lower right-hand stroke should not extend further than the right-hand side of the circumscribed parallelogram.
Figure 2. The figure 2 is constructed by starting at the left hand side of the circumscribed parallelogram and continuing tangent as indicated in the figure at points 2, 3, and 4. The lower part 4-5 should in all cases be horizontal and it should never extend further than the right-hand side of the circumscribed parallelogram.