GIFT OF MICHAEL REESE MECHANICA-L DRAWING. WRITTEN FOR THE USE OF THE NAVAL CADETS AT THE UNITED STATES NAVAL ACADEMY. BY F. W. BARTLETT, Lieutenant Commander U. S. Navy. FIRST EDITION. FIRST THOUSAND. NEW YORK: JOHN WILEY & SONS. LONDON: CHAPMAN & HALL, LIMITED. 1901. Copyright, 1901, BY F. W. BARTLETT. ROBERT DRUMMOND, PRINTER, NEW YORK, PREFACE. THE attempt is made in this treatise to find the methods of practical work in use in most drafting-rooms and to give these methods in detail for the use of those studying Mechan- ical Drawing. The author has endeavored to eliminate any personal peculiarity of method, and has based the treatise on the methods in use in the United States Navy, as far as these methods could be determined. As general methods differ slightly, the drawings referred to for the general instruction have been those of the Bureau of Steam Engineering of the Navy Department, and the methods of that bureau have been followed. The special methods of the Bureau of Ord- nance and of the Bureau of Construction are studied and used after the main course is completed. The differences are, however, slight and refer principally to center lines and dimension lines. The Bureau of Ordnance uses the decimal scale also. All the minor points of method that are found only by experience cannot be given to a large class by a small corps of instructors, and the endeavor is made to place these methods where they may be found and studied. The in- structor may then refer each one to the book instead of giving to each individual the same detail. 92320 IV PREFACE. The system of instruction urged does away with copying. In fact, no copying is allowed and no drawings are available for copying. The First Drawings are purposely full of detail, so that the eye, mind, and hand may be trained to accuracy together, each depending on the others. The instruction lessens as the figures follow each other, only the new and most impor- tant points being noticed. The attempt is made to have the triangular scale used so that it will be thoroughly understood. No Geometry or Descriptive Geometry is given, as these branches are taught in another department at the Naval Academy. All but Sheet III has been carefully criticised by Mr. A. M. P. Maschmeyer, Chief Draftsman in the Bureau of Steam Engineering at the Navy Department, and the author is much indebted to him for his kindness and his thorough criticism. The naval officers associated in this work have assisted materially with suggestions. I am particularly indebted to Lieut. Commander John L. Gow, U. S. Navy, for his un- sparing and accurate criticisms. F. W. BARTLETT, Lieut. Commander, U. S. N. CONTENTS. PACK THE DRAWING COURSE ix USE OF INSTRUMENTS i Drawing-board i Thumb-tacks .... 2 Pencils and Pencilling 2 Sharpening the Lead 3 Ink 5 Red Ink 6 T Square 6 Triangles 8 To Test Triangles 9 The Triangular Scale 10 To Use the Scale 13 Triangular-scale Guard 13 Right-line Pen 13 Use of the R. L. Pen 14 To Examine and Test the R. L. Pen 18 To Sharpen the R. L. Pen 18 Compasses 19 To Test the Compasses 20 To Use the Compasses 20 Extension-bar 21 Bow Spacers 22 Bow Pencil and Bow Pen 23 Dividers 24 To Use the Dividers 24 Irregular Curves 25 Protractors 26 To Use the Protractors 26 Erasers 27 Erasing Shields 28 Horn Center ' 28 Brushes 29 v VI CONTENTS. PAGE Pricker 29 Beam-compasses or Trams 29 Foot Rule 30 Calipers 30 Splines 31 Lead-wire ' 31 Paper-cutters 31 GENERAL DIRECTIONS 32 Stretching Paper 32 Profile Drawings 34 General Arrangement 34 Working Drawings 35 Views 36 Projections 38 Lines 40 Center Lines 41 Shade Lines 43 Shafts and Other Cylindrical Objects 49 Sections 50 Hatching 51 Breaks 56 Dimension Lines; Dimension Extension Lines 57 Threads 62 Square Threads 67 Bolts and Nuts 70 Jam-nuts 74 Tails 74 Working, Border, and Cutting Lines 75 Legend, Lettering, Scale, etc 76 Block Letters 79 Free-hand Lettering 83 Scales 83 Line Shading and Tinting 85 Flat Surfaces 85 Cylinder 86 Interior of Hollcw Cylinder 89 Cone 89 Sphere 91 Tinting 92 To Prepare the Tint 92 To Lay on a Flat Tint 93 Stippling 95 Tinting. Cylinder 96 Cone 97-98 Sphere 98 CONTENTS. vii PAGE Tracing Q5 Blue-printing 98 Sketches go, Plan of Procedure in Making a Drawing IO 2 Pencilling the Drawings IO 3 Plan of Procedure in Inking IO 4 General Remarks 105 FIRST DRAWINGS 106 General View of Sheets I and II 106 Sheet I. Straight-line Drawing 107 Fig. i. Horizontal Full Lines ioy 2. Vertical Broken Lines no 3. Horizontal Heavy Lines m 4. Vertical Heavy Lines 113 5. 45 Triangle 114 6. 45 Triangle 115 7. 60 Triangle 116 8. 60 Triangle 117 9. 45 Triangle 119 10. 45 and 60 Triangles 120 11. 45 and 60 Triangles; no T Square 121 12. 60 Triangle 122 13. Bow Spacers 124 14. Dividing Lines into Parts 125 15. Dimension Lines and Figures 12^ 16. Section: Hatching 128 17. Line Shading 129 18. Protractor 130 Legend 132 Sheet II. Curved-line Drawing 133 Fig. i. Compass 133 2. Compasses, Bow Pencil and Pen. ... 135 3. Bow Pencil and Pen 136 4. Bow Pencil, Bow Pen, Bow Spacers 137 5. Fillets 138 6. Arcs and Straight Lines 140 7. Two Arcs and Straight Line Joining Them 143 8. Protractors, Arcs, and Straight Lines 145 9. Tangent Arcs 146 10. Connecting Arcs 147 11. Connecting Arcs 148 12. Extension-bar 150 13. Ellipses; Irregular Curves 151 14. Irregular Curves 153 15. Shading Fillets 154 Vlll CONTENTS. PAGE Fig. 16. Shade Lines 155 17. Heavy Lines with Narrow Space Between 156 18. Shading Circles; Hatching 157 Legend 158 Sheet III. Projections, etc. Working Drawing 159 Description of Models. General Directions 159 General Description of Sketching 160 General Directions for Drawing Sheet III 163 Legend 163 Positions of Views on Sheet 164 Model I 165 Sketching 165 Dimensions 167 Sections 168 Directions for Drawing 170 Model II 171 Sketching 171 Dimensions 174 Section 174 Directions for Drawing 175 Model III 176 Sketching 176 Dimensions 178 Section 179 Directions for Drawing 179 Legend, Sheet III 181 STANDARD DIMENSIONS OF BOLTS AND NUTS FOR THE UNITED STATES NAVY 182 STANDARD HATCHING 183 SPECIAL METHODS OF THE BUREAU OF ORDNANCE, U. S. NAVY 184 SPECIAL METHODS OF THE BUREAU OF CONSTRUCTION, U. S. NAVY... 185 INDEX 187 ERRATA. Page 8, line 7. For twice read half Page 13, line n. Add: When several dimensions are to be measured along the same line, do not shift the scale for each one ; leave it in the first position and make all the marks. This lessens the danger of making errors. Page 29, line 30. Add : Press downward with a twist ; this gives better control. Page 39, Fig. 17. Continue extension line, second horizontal from top. Make broken the horizontal lines between views, at bottom of plan and at top and bottom of elevations. Page 44, Fig. 18. Figure inverted, and A for B Page 54, Fig 37. Shade right side of head of bolt. Page 6 1, line 5. Add : Dimensions so carried away are placed so as to be read from the same direction as if in their correct posi- tions. Page 63, Fig. 49. Top and bottom lines solid to limits of bolt. Bottom one a shade line. Page 73, Fig. 64. Only the outline of the nut should be shaded. Page 74, Fig. 67. No shade line between the jam-nuts. Page v i 10, figure. Place dimensions at top vertical, as J". Page 112, line 25. Add : Draw the upper five lines like those to the right. Page 113, line 9. For "375 read '.'375 Page 113, line 20. Add : Draw the first five lines from the left like those above. Page 118, line 5. For 60 read 30 Page 131, line 19. For 62 75' read ^f 15' Page 135, line 13. For 1/4" read 3/8" Page 167, sketch. Draw vertical center line. Page 177, last sketch. For Half section on CD read Half sec- tion on AB. THE DRAWING COURSE. IT is considered that the most important parts of the course are : First. Instruction in the use of the instruments; in mak- ing clean, sharp lines; in connecting lines cleanly together; the technique generally. Second. Instruction in quickly and accurately making a correct, dimensioned sketch of any piece of mechanism ; and from the sketch making a working drawing so that the mechanism may be reproduced with certainty. Third. Instruction in carefully and accurately making tracings and blue-prints from either the inked or pencilled working drawings. Fourth. Instruction in quickly and accurately reading drawings. Fifth. Special instruction in engineering, ordnance, and ship-building methods. MECHANICAL DRAWING. USE OF INSTRUMENTS. NOTE. As center lines cannot well be printed in red ink, all center lines are drawn as fine broken lines with long dashes and short distances between the dashes. Drawing-board. One edge only of the drawing-board is made a true plane. The accuracy of the drawings depends on this plane being true. This is the ''working-edge" and is marked by a circular stamp along the middle of the upper face of the board. When in use, this ''working-edge "is at the left, the stamped face upwards. The "working-edge " of the board is considered for con- venience as the W. side of the board, so that the side away from the position of the draftsman is the N. side of the board, etc. The lines from E. to W. on the board are considered hori- zontal lines; those from N. to S. vertical lines. When beginning a new drawing, take the drawing-board and T square to the pattern-maker to have them " trued up " ; in other words, to make the "working-edge" of the board and the sliding-edge of the T square true planes. At the same time the T square is tested to make sure that the top edge of the blade is at right angles to the sliding-face of the head. 2 ME CHA NIC A L D RA WING. The drawing-board is to be kept horizontal or very slightly inclined at the height desired, the work done standing. When first beginning work, swing the board around until the best light is obtained, the direction of the light to be from the left-hand top (N. W.) corner. Test this by placing the T square and triangle in position and noting if the edges to be drawn by are in light or shadow. While drawing, test often for light, as the work will be poor if the light is bad and the eyes will suffer. Thumb-tacks. These are used in securing drawing- and tracing-paper on the boards. When first inserted in the paper the heads may be tipped at an angle towards the center of the paper, so that when straightened up in pushing them into the wood they may slightly assist in stretching the paper. They are always pushed down firmly when used. To secure paper or tracing-cloth on the boards. Place the paper in position as desired ; put in a thumb-tack at the middle of the top line of the paper; slide the hand with a gentle, firm pressure from this tack down to the middle of the bottom line of the paper and, while firmly holding the paper as stretched, insert another thumb-tack; begin at the center of the board and slide the hand to the right with the same pressure and insert a tack at the middle point of the right-hand line of the paper; do the same to the left; begin again at the middle of the board and slide the hand with the same pressure towards a corner and insert a tack ; repeat for the other corners. In each case, be sure to keep the pressure until the tack is fast. It may be necessary to insert tacks between those already placed. In each case press the paper as described. Pencils and Pencilling. The pencil-work of a drawing is most important. Good ink-work never hides defects of bad pencil-work. The accuracy of the drawing depends almost entirely on good pencil-work. Make clean, sharp lines not faint ones; it is difficult in USE OF INSTRUMENTS. 3 inking or tracing a drawing to find the faint lines, and the eyes are strained by the close vision required. Even though slight depressions are made in the paper by making firm lines, it is best to do this and save the eyes. Draw all pencil-lines full and broken as required. It is a waste of time to begin and stop the pencil-lines at the exact points where the ink-lines will begin and end. Sweep through the terminal points of the line, but no farther than necessary. Pencil-lines are easily erased after the inking is completed. The leads in the pencils used should be HHHHHH or HHHHHHH. These marks are found on the pencil or on the box of leads used with the artist's pencil. Never use a soft lead for any purpose on a drawing-board. Sharpen the pencil-points frequently The best point for the pencil is the long chisel-point narrowed to about one-third the thickness of the lead. Fig. i shows the proper sharpening of the lead-pencil The longer bevels are from 2" to 3" long, and the shorter ones from \Yz" to 2" long, axially. Fig. 2 shows the proper method of sharpening the lead for the artist's pencil. The length of the longer bevel along the axis of the lead is from $/%" to yd". It is even advisable to make the point thinner as in Fig. 3, but there is more danger of breaking the lead through care- lessness. For the compasses and bow pencil, narrow the flat edge still more and take care to place the flat edge of the pencil-point so that it is tangent to the arc drawn. Another good point is made by sharpening the lead with a cut clear across at an angle, as shown in Fig. 4. This method is by many considered best, as the outer skin of the lead is hardest and wears better. Also, less time is required for sharpening, and the point is rounded. It is considered especially good for compasses and bow pencils. Sharpening- the Lead. If a file is used, the lead is sharp- ened by rubbing it along the rougher side of the file until it is MECHANICAL DRA WING. shaped and then finishing on the smoother side of the file. Support the end of the file when sharpening the lead. In the last sharpening, roll the lead a little on the file so as to round the corners slightly. Finally, rub the flat edges on a piece of drawing-paper, rolling as before; this will remove the rough edges left by the file. USE OF INSTRUMENTS. 5 As files soon wear out, many prefer pads made of strips of sandpaper. It is a good practice to have one end of the pencil sharp- ened with a chisel-edge and one with a round (needle) point for marking dimensions, both leads hard ; but it is better for very accurate work to mark off dimensions with the sharp points of the dividers or bow spacers; or, better still, if such an article is at hand, the pricker. In using the pencil, keep it nearly vertical and keep the arm away from the body. Do not hold the pencil so that the point is in the angle between the guiding-edge and the paper: keep it vertical. Use the pencil with a free sweep, keeping the eye along the line of the T square or triangle if possible. Always draw from left to right, and always away from the body. Considerable practice will be required in order to draw a line accurately through two points when the pencil is guided either with the T square or the triangle. In the case of the triangle, for instance, if the two points are marked and it is desired to draw a line through the middle of each mark, place the triangle very near the points but not exactly up to them, as the pencil must be held vertical and not bent over to fit sharply into the angle between the triangle and the paper. Hold the pencil properly and draw a short line through the left-hand point; if it is not in the center of the mark, the tri- angle must be moved a little and the attempt repeated. After the line is correct, carry the hand along in the same position to the other point and again test by a short line. When the two short lines agree with the centers of the two marks, return to the left and sweep the line across, carefully holding the hand in the same position and resting the last two fingers on the triangle. Ink. The best drawings can be made only by using the best Indian or Chinese ink. This consists of carbon mixed with O MECHANICAL DRA WING. some adhesive substance, and lies wholly on the surface when used on the drawing-board, and can be readily erased if neces- sary. It is furnished in blocks of varying sizes, and is ground in water in any convenient receptacle. Special forms of ink- saucers are made with glass covers to reduce evaporation and keep out dust. As considerable time is required to mix the ink, and as ink must be freshly mixed to be good, it is often necessary to use one of the kinds of permanently mixed inks furnished in bottles. The results are not as good as can be obtained with the stick ink, but the time required for mixing the ink cannot always be spared. Red Ink. This is used for center lines, etc. It flows more freely than the Indian ink, and greater care must be observed in its use, as it is much more likely to run out of the pens agi.inst the triangles and T squares. The outside of the pen must be carefully wiped after the pen is filled; the pen must not be filled as full as with the black ink; and care must be taken nc t to hold the pen too near the triangles or T square when making lines. Except where a section is marked, all red-ink lines are fine lines. T Square. On the working-edge of the drawing-board and on the T square depend primarily the accuracy of the drawings. The T square consists of the head and the blade. Some- times they are fixed at right angles to each other; and some- times the blade is movable and may be clamped at any desired angle with the head. The fixed blade answers all practical purposes for general work. The sliding-edge of the head of the T square is made a true plane, and this edge slides along the " working-edge " of the drawing-board, so that all lines drawn along the blade in the various positions of the head will be parallel. In the fixed-blade type, the top of the blade is accurately planed so USE OF INSTRUMENTS. 7 as to be at right angles to the head, so that all lines drawn along this top of the T square will be at right angles to the "working-edge" of the board. Since the triangles are accurately squared, the vertical lines drawn when the triangle rests on the T square in position will be parallel to the ' ' working-edge ' ' of the board. Lines should of course be drawn with the upper edge of the T square only as a guide. The T square is used for all horizontal lines. It cannot be depended upon for the vertical lines, as the bottom of the board is not planed at right angles to the " working-edge." It is held with the head firmly pressed against the " work- ing-edge " by the left hand, and is moved along that edge by the left hand. It must never be moved with the right hand on the blade or with both hands pushing the blade, or with the right hand assisting the left by pushing on the bla le at the same time as the left hand moves the T square. Stretch the first finger and the wrist of the left hand along the head of the T square equally on both sides c5 the blade, making the support as long as possible. The vertical lines are drawn by using the iriangles as guides. These are moved along the T-square as it is firmly held in position with the left hand. As both hands are required in using the triangles in this manner, after the triangle is nearly in the proper position, slide the left hand along the blade of the T square, always pressing to the right and down- ward, and hold the T square with some of the fingers and move the triangle along with the others. Often test the posi- tion of the T square by moving the left hand back to the head of the instrument, again sliding it along the blade as before. Never guide a knife in cutting paper with the upper edge of the T square. Use the lower edge; or, better still, use the knife with no guide but the eye and the line drawn for cutting. Use no weights to hold the T square or triangles in posi- tion. 8 MECHANICAL DRAWING. Triangles. The triangles are 45 and 60. The 45 tri- angle has equal angles at the ends. The 60 triangle has one 60 and one 30 angle. The other angles of both triangles are right angles and are very accurately constructed. In the case of the 45 triangle, the two shortest sides are equal in length ; in the 60 triangle, the shortest side is twice the length of the longest. The triangles rest against the T square and are used in drawing the vertical lines of the drawings. These lines are then parallel to the " working-edge " of the drawing-board. In drawing these vertical lines always place the triangle on the T square so that the left side of the triangle will be the one ver- tical. In this manner the light will always come from the left. To Draw Parallel Lines with the Triangles. After one line is drawn with a triangle, to draw others parallel to it, place the triangle near the line and parallel to it, as if the line were to be drawn again. Do not attempt to place the triangle edge exactly on the line, as it will be found very difficult to get it exactly right, whereas it may be readily brought near and parallel. Hold this triangle firmly and bring the other triangle against one edge of it; then hold the second one firmly and move the first one along the edge of the fixed one until the desired point is reached, when the line may be drawn. This may be repeated for a number of lines parallel to the first one drawn. The left hand must hold both triangles when the lines are drawn, some of the fingers on each; generally the thumb and last two fingers hold the fixed tri- angle, and the first and middle fingers move along and secure the one moved. Angles of 15, 30, 45, 60, 75, and 90 may bj FIG. 40. A variation is sometimes made in the method of making the break, as shown in Fig. 40. This shows the material, the hatching being- done in accordance with the "Standard Hatching. " Often breaks are made of small portions of a piece of mechanism in company with a portion of a section, as shown in Fig. 41. FIG. 41. In order to show the kinds of metals, and to make more clear the interior of the mechanism, the irregular break is made. It is considered that this break extends inward to the center line and that the top half is removed. This irregular break is drawn as before with a R. L. pen used carefully. Dimension Lines. Dimension Extension Lines. Besides drawing the views of an object to correct size or to a certain scale, the dimensions of all parts of the object must be clearly placed on some of the different views, so that whoever may 58 MECHANICAL DRAWING. have occasion to use the drawing will not be obliged to measure any dimension. Auxiliary lines are used for these dimensions. They are light, broken lines in red ink and are drawn after the center lines are completed. The lengths of the dashes vary with the lengths of the lines. When the dimension between two points is to be given, a red, broken line is drawn from one point to the other, leaving a break near the center for placing the dimension. This line is drawn directly to the points and terminates at these points. The dimension is placed in the space left, and at the ends of the line are placed arrow-points, the points of the arrows exactly at the extremities between which the dimension is taken. See Fig. 42. FIG. 42. Frequently dimensions are given directly on the views of the object; but when this method crowds the drawing, the dimensions are placed beyond the outlines, and the distance to be marked is carred out from the outlines by dimension extension lines, as in Fig. 43. \ ~T~ i I \ S- t i i i i ! \ i i i | 1 , _*_- / ~ s~ 1 I \ i *- -Hrh ""7T <- -Y- FIG. 43. The position of the dimension lines is a matter of judgment, but the greatest care must be exercised not to complicate the GENERAL DIRECTIONS. 59 drawing and not to repeat the dimensions on the different views unless this may make a complicated drawing easier to follow. Where two views are beside each other, corresponding points are often connected by dimension extension lines and the dimension lines drawn between these, as in Fig. 44. T FIG. 44. When dimension lines are outside of the views, these lines are placed at least %" away from the outlines of the figures. Center lines are never used for dimension lines, and the figures for the dimensions are not made over the center lines. The center lines are left as clear as possible. If it can be arranged without too much difficulty, dimen- sions are not placed on hatched portions of the drawing ; but, if it is necessary to do this, leave irregular spaces in the hatch- ing so that the dimensions may be placed at these points. Group dimensions that are for portions of the drawings that are alike; that is, place them near together. 4 4 Over-all dimensions ' ' should always be given for con- venience in getting out material for work. This means the dimensions of the greatest limits of the object in the directions FIG. 45- of the three center lines at right angles. These are generally outside of the figures and should be beyond all the other dimensions that are outside the figures, as in Figs. 43 and 45. The figures for the dimensions are placed so as to be read from 60 MECHANICAL DRAWING. the bottom or right-hand side of the drawing-board. They are placed so that the middles of the figures and the horizontal line of the fractions are in line with the dimension line ; and the figures are at right angles to the line. As the dimension lines are drawn before the figures are made, spaces must be left while drawing the dimension lines. This requires especial care in dimensioning diameters of circles, as in Fig. 46. FIG. 46. FIG. 47. All the dimension lines are in the two quadrants, as shown. Diameters, not radii, are dimensioned where possible. If radii must be dimensioned, place the arrow-heads at both center and circumference, as in Fig. 47. Dimension extension lines are broken lines made with red ink and extend a short distance beyond the points where the dimension arrows are placed. See sketches 43 and 45. The dimension and dimension extension lines are made with dashes from y%" to y" long, depending on the lengths of the lines. The spaces between the dashes vary from ^V' to ^" . These lines are never heavy lines. Arrow-points are drawn in black ink with a fine writing- pen not with the R. L. pen and the points of the arrows touch the lines between which the dimension is to be given The diverging lines of the arrow-heads make an angle of about 60 with each other. These diverging lines are light, clean lines from i/ie" to y%" long. GENERAL DIRECTIONS. 6 1 When the distances are small, these arrow-heads are placed on the outsides of the lines, pointing towards each other, and the dimension is either placed between the points or is carried to one side with an arrow pointing towards it from the space to be measured. See Fig. 43. The figures for marking the dimensions are made in black ink with a writing-pen that is not too fine. They are made clear and prominent. The shorter dimensions must have as prominent figures as the large ones. These figures are y%" high and stand at right angles to the dimension lines. When fractions are used, the line separating the numerator and denominator is horizontal, as x/ , not 3/4 " . When mixed numbers are used, the inch sign is placed after the fraction, as 2f' 7 , not 2"|. When dimensions are given in decimals, the inch sign (") is placed over the zero mark; as, 2/375, not 2.375". Up to and inclusive of 24", dimensions are given in inches; beyond 24", the dimensions are given in feet and inches. For feet use "ft." or "feet," instead of the character '; as, 2ft. 6". Dimensions are given in feet, inches, and fractions of inches. The fractions of inches used are halves, quarters, eighths, sixteenths, thirty-seconds, and occasionally sixty- fourths. Fractions are always reduced to their lowest terms. The total height of the fraction is about }^" The diameters of cylinders and strokes of engines are given in inches. These are practically the only exceptions to the above. In locating bolts or holes, if they are uniform on both sides of the center line, draw a circle in red ink through the centers and give the diameter of this "bolt circle." This gives the distance between the centers of opposite bolt-holes and thus the radius of the bolt circle. Mark the center of each bolt- hole with a short radial line in red ink. If they are not uniform, give the distance from the center line to the center of the bolts. Occasionally it is necessary to 62 MECHANICAL DRAWING. give the distance between the center of the bolt or hole and the nearest edge of the object; but, in general, distances should be given from the center lines. See Fig. 48. I FIG. 48. The number of bolt-holes defines the angular distance apart. On the drawing-board do not draw the dimension exten- sion lines and dimension lines in pencil, and do not put down the dimensions in pencil unless a tracing is to be made from the pencilled work. This is all done in ink after the drawing is completed. On the drawing-board draw first the dimension lines and then the arrows ; this is reversed in sketching. Threads. The screw-thread cut on a bolt is for the pur- pose of allowing the bolt to advance in the hole as it is turned around. As the bolt turns around once it advances a certain distance, called the " pitch" of the thread. The nut that may turn on the bolt has a thread cut on the inside with the same pitch as the thread on the outside of the bolt. The thread cut on the bolt is called a " male " thread, and that in the nut a "female " thread. If we follow the top of an ordinary screw-thread around the bolt, we find that for a complete revolution we have advanced one thread. Hold the. bolt in a vertical position and the front elevation of the bolt shows that the view of the path of the point we followed is a curve. This curve slopes upward from left to right and then passes behind the. bolt and slopes upward from right to left ; it reappears at the top of the next thread. GENERAL DIRECTIONS. 63 Thus we have advanced one pitch. In half the revolution one half pitch \vas advanced. The same happens if we follow the path of the bottom of the thread. To represent the threads on the drawing-board, draw the center line and draw parallel to it lines for the outside diameter of the bolt. FIG. 49. Lay off on the left side the pitch lengths ab, be, cd, etc., and the half-pitch lengths at i, 2, 3, etc. Draw horizontal lines through these points. Then the top of one of the threads will be represented by the curved line from a to a , as the dis- tance travelled longitudinally for one half-revolution will be one half-pitch. The other half of the revolution will cause the top of the thread to travel behind the bolt in a line represented by the dotted line ab. The other tops of the threads will be parallel to these two lines, as the same cycle is repeated farther along the bolt. The thread represented is called a triangular thread, and the standard angle for the sides of the thread is 60. From 6 4 MECHANICAL DRAWING. the points a and b draw 60 lines to meet on the line of half- pitch at e. This, then, is the position of the beginning of the root of the thread. The root will advance to e' in one half- revolution and the moving point will follow the curved line ec' ' . During the other half-revolution this point will follow the curved line e'f behind the bolt. These lines, aa'b and ce'f, represent, then, the form of one thread for one revolution. As the other threads are exactly the same, they are simply copies of this first one. The curves made are readily found, as they are helices, and for every portion of a revolution an equal portion of the total pitch is passed over longitudinally. It is customary to shade the bottom of the thread, as in Fig. 50. The rest is shaded according to the general plan. In making drawings, these lines are seldom drawn as curves. They are so near straight lines that they are usually represented as straight. Fig. 50 shows the appearance of the FIG. 50. FIG. 51. threads as drawn when threads are represented at all. The straight lines simply replace the curved ones, and the broken lines are not drawn. To still further simplify the representation of threads the portion to be threaded is shown as in Fig. 51. The finer lines, I I, 2 2, etc., represent the tops, and the heavy lines the bottoms, of the threads. The distance apart GENERAL DIRECTIONS, 65 of the lines is not measured, but is spaced by eye as in hatch- ing. This distance varies for different diameters, being smaller for small bolts to represent approximately the number of threads per inch of length. The finer lines are drawn first. In order that the heavy lines may begin and end uniformly, draw fine pencil-lines on either side and equally distant from the side lines of the bolts, as ab, cd. Draw the heavy lines with these lines for guides for the beginning and ending, and place them by eye in the middle between the light lines. To still further simplify the representation, sometimes the heavy lines are omitted entirely, but this is not customary except for very small bolts. To find accurately the angle at which to draw these repre- sentative lines it is first necessary to know the number of threads to the inch. If the drawing is made from a model, lay a rule along the top of the thread so that one ridge corresponds \vith any inch- mark of the rule. Count the number of ridges for one inch of length. If the number is 6, 8, 10, etc., this gives the fraction of an inch occupied by the length of one thread, or the pitch. If there is no model and the bolt is standard, consult a Table of Standard Bolts and Nuts, which will give the number of threads per inch for the diameter of bolt required. A Table of Standard Bolts and Nuts for the United States Navy is found at the end of the book. Lay off this length on the left side of the bolt and draw two horizontal lines through the marks. Since the thread must advance longitudinally one-half of one of these divisions for the half revolution, one-half this height will show the limit- ing height of the right-hand end of the line. See Fig. 52. The lines through a and b are apart a distance equal to the pitch. The line through c is at the half-pitch. Then ad is the line sought. As a rule, the slope of the line may be determined with 66 MECHANICAL DRA WING. sufficient accuracy by eye. As the height of this line longi- tudinally is one half-pitch, double this height must separate the lines longitudinally. See Fig. 53. After drawing ad with the slope determined by eye, project d across to />; double ab\ ac is the pitch, and the next line begins at c. FIG. 52. FIG. 53, After having determined the position of the lines for the top of the thread the lines for the bottom may be drawn as above. When a bolt is turned to the right, or so that the top of a thread moves to the right and down, or in the direction of the hands of a watch, the thread on the bolt is called a "right- handed thread." All of those drawn are right-handed. The slope is the opposite for the "left-handed thread." These left-handed threads are used only for special purposes. When a section is cut through the center of a threaded hole, the part of the female thread seen beyond the section corresponds to the hidden part of the thread on a bolt, and the slope is in the opposite direction. The shading of the female thread is the same as that of the male thread, the heavy line at the bottom of the thread. When the section goes through the bolt in position in the bolt-hole, the bolt is drawn in elevation resting in the section. As a rule the threads are not drawn and the bolt and hole are represented as in Fig. 54. As the drill used for drilling the hole is ground at an angle of 60, the bottom of the hole is GENERAL DIRECTIONS. 6 7 finished by the two lines making an angle of 120 with each other. The end of the bolt is rounded off as a rule, the common radius being the diameter of the bolt. The bolt is FIG. 54- represented as screwed to the bottom of the cylindrical part of the hole. Square Threads. The threads drawn in the figures are all triangular, which is the common type ; but square threads are used for many special purposes. The only difference is in the shape of the thread. The pitch and methods of finding the curves for the top and bottom are the same. FIG. 55- The pitch-length outside the solid metal is filled, in the case of the triangular threads, with a triangular-shaped figure 68 MECHANICAL DRAWING. and a space of nearly the same shape. In the case of square threads the portion for the metal and the space remaining are both rectangular. These may be equal and may differ greatly, as in Fig. 55. These threads are represented as in the case of triangular threads. When the drawing is large and ornamental, the helices are drawn ; ordinarily straight lines are used. The lines for the depressed portions may be left out as a rule. See Fig. 56. FIG. 56. The pitch may be taken up by a single thread, when the thread is called "single screw"; or the length of the pitch may be filled by two or more threads, when the thread is called "double screw," "triple screw," etc. To determine to what class a screw belongs, follow a ridge FIG. 57- around for one revolution and find how many ridges there are between the original point and the one arrived at after going around. Double, triple screws, etc., are used wherra greater GENERAL DIRECTIONS. 69 longitudinal movement is desired ; in other words, when the pitch is increased. Then the space between the following threads is filled in by extra threads for strength. Fig. 57 shows a single screw of great pitch. It is noticed that most of the bolt is cylindrical. For strength, there are placed between the threads two extra ones PITCH FIG. 58. that have the same pitch as the original one. Fig. 58 shows a triple screw as usually drawn. When the threads are double or triple, or when the thread is other than standard, it is stated on the drawing near the bolt. Hidden threads are never drawn except in the case of very large threads inside of nuts, as in the case of a propeller nut. In this case the threads are shown in broken lines, unshaded. When threads are drawn on bolts, it is seldom advisable to make the exact ending of the threads as it is in reality. FIG. 59. The tops and bottoms of threads are ended as in the sketch. The real ending of the top of the thread is behind the bolt somewhere. The bottom has to be ended according to how the curve or other line at the bottom cuts the teeth of the thread. 70 MECHANICAL DRAWING. Bolts and Nuts. As most bolts are standard, the dimen- sions are obtained from the Table of Standard Bolts and Nuts. If the bolt differs from the standard, the points of difference are shown on the drawing. The diameter of the bolt is determined either by calcula- tions for strength or by custom. The ordinary bolts used in machine work have hexagonal heads; the square-headed bolts are used for rough work or for special purposes. The height of the bolt-head and the long and short diameters are given in the Table. The length of the bolt is determined by the neces- sities of the special case. After the head of the bolt is shaped, the top edge is chamfered off at an angle of 45. This is done by centering the bolt in a lathe and cutting the chamfer as the bolt revolves. This chamfer as a rule is cut just enough so that the sharp corners are removed, and so that the flat sides are left at the full height at the center. This is shown in Fig. 60. FIG. 60. The point /"shows that the middle of the flat side is left at its full height, while at g the sharp corner is citt off. The GENERAL DIRECTIONS. Jl chamfer makes a cone of revolution which cuts the flat sides ; the curves of intersection are hyperbolae ; but the projections of these hyperbolae are so nearly circles that they are drawn as circles. Where the cone of chamfer cuts the top plane, the intersection is a circle, as shown in the plan view. The exact representation of the top of the bolt or nut is shown in Fig. 61, but the 45 lines are seldom drawn in practice. From the Table of Standard Bolts and Nuts it is found that the height of the nut is the same as the diameter of the bolt, while the height of the bolt-head is less, as a rule. FIG. 61. FIG. 62. In drawing the nut, from the point a with a radius equal to the diameter of the bolt describe an arc, as shown. See Fig. 62. This is approximately the curve for the middle por- tion ; the continuation of this curve defines the limits of the long diameter of the nut. The continuation of the lines of the bolt defines the limits of the central face. Draw the four verti- cals and a horizontal line cf through c. Draw a vertical center line for the face be by means of small arcs from c and c, and find a center on this line that will cause an arc to pass through the points c and e and tangent to the top line. Note that, as usually drawn, the line across the top of the nut ends at and is tangent to the top of the curves for the side faces, and is tangent to the curve of the middle face. In drawing the head of the bolt (see Fig. 60), the height is laid off from the Table and the top line drawn. From the 72 MECHANICAL DRAWING. center of this top line lay off along the center line of the bolt the distance d. Beginning with this point, a, as in the case of the nut, find the centers for the side faces. To draw the other view of the bolt-head (Fig. 60), the widths of the faces are projected from the plan, and the points where the curves begin are projected from the other view drawn. These curves must have centers in the middle lines of the faces and must be tangent to the top line. The center is generally found by trial, but the length of the radius is about four-fifths of the diameter of the bolt. Although Fig. 60 shows the correct way to represent a bolt according to the general plan, it is customary to place the Side Elevation under the Plan. The reason is that the Front Elevation cannot be drawn until the Side Elevation is com- pleted, as the limits of the curves have to be determined from the Side Elevation. Hence it is the custom always to draw the Side Elevation of Fig. 60 first for any representation of a bolt. If two views of the bolt are made, the second one drawn is the Front Elevation of Fig. 60. In other words, the first view shows the long diameter of the bolt-head. In the Plan it is not good practice to draw a broken line to show the diameter of the bolt. Where a number of bolts or nuts are drawn, either in a straight line or in an arc of a circle, the heads always face the same way, whether in Plan or Elevation; the faces of the nuts are drawn facing in the same way as the bolts for each view. FIG. 63. Sometimes bolts are made with square shoulders under the head so that they will not turn when in place. The conven- GENERAL DIRECTIONS. 73 tional way of representing this square portion at any part of a body generally cylindrical is shown in Fig. 63. The portion with the crossed lines is the flat-sided portion. For rough work only, where the nuts are stamped out and FIG. 64. unfinished, the nuts are screwed on the bolts with the rounded side down, as in Fig. 64. Bolts that are finished always have the bottom portion slightly cut away at the projecting corners, so that these corners will not cut into the metal. When bolts and nuts are drawn in place, the bolt is repre- sented as projecting beyond the nut slightly. When threads are drawn on the bolt beyond the nut, represent the extension FIG. 66. FIG. 65. of the bolt as in Fig. 65. The bottom of the thread is pro- jected to the top of the nut on either side of the center. An 74 MECHANICAL DRAWING. arc is drawn through these two points, using the middle point of the bottom of the nut as a center. When threads are merely represented on the bolt, show the extension of the bolt as in Fig. 66. The outside diameter of the bolt is projected to the top of the nut, and short lines are drawn and an arc drawn across with a radius equal to the outside diameter of the bolt. The height, of the short lines drawn varies with the diameter of the bolt. Jam-nuts. These are two nuts screwed tight together on a bolt, each one preventing the other from turning. These are generally of different thicknesses and are represented as in Fig. 67. FIG. 67. The nut nearest the end of the bolt is thicker than the first one screwed on. Both edges of both nuts are chamfered. When bolts are standard, the dimensions given are diameter, length under head, and length of the threaded portion. When bolts are not standard, in addition to the above there are given the height of the head, either the long or short diameter of the head, and the number of threads to the inch. Tails. When two curved surfaces meet at angles with rounded corners to prevent sharp angles and so that the defin- ing lines of one of them disappear, it is customary to represent this effect by short curved endings called "tails." The small projections represent bosses for bolts and are cylindrical. They gradually meet the rounded larger surface with small GENERAL DIRECTIONS. 75 curves at the junction. "Tails" are placed at the ends of the vertical lines to represent this effect. I FIG. 68. Working, Border, and Cutting Lines. The working line encloses a rectangle beyond which the drawing may not extend, as a rule. It is laid off from the center of the paper both ways, using the 16 scale. The center is found by draw- ing with the T square diagonals from opposite corners of the paper (not the board). This line is pencilled but not inked. The idea of it is to leave a space between the drawing and the border line for a good effect and to avoid confusion. In special cases, where the scale of the drawing would have to be made too small on account of this line, it may be surpassed. The border line is ornamental only in that it gives a finish to the general effect of the drawing, and the blank, irregular spaces of the paper beyond the drawing are made less promi- nent. This line is drawn in pencil after the working line is drawn, and is at a certain distance outside of the working line. It is inked after the drawing is completed. Border lines are often very ornamental, and much time and care may be expended on them when an especially ornamental drawing is to be made ; but, as a rule, little time may be put upon them, as other work is more important. It is a good effect to shade the lower and right-hand border lines. The upper and left-hand lines are made of fair width, and the other lines at least four times as heavy. Plain lines meeting at points are sufficiently effective. Occasionally small 7 6 MECHANICAL DRAWING. portions of the drawing may project beyond the border line. In this case interrupt the border line for half an inch on either side of the outline passing beyond it. The cutting line is outside of the border and is drawn in pencil after the border line is marked. This line is simply a guide for cutting, and is not inked. When the line is drawn, it may be found that portions of the paste used in stretching the paper may be so far in that there will be difficulty in cutting off the paper finally; in this case, all the lines may be moved farther away from this side ; or it may be necessary to change the dimensions of working, border, and cutting lines, as is most convenient. In marking the working, border, and cutting lines, the half- distances enclosed by these lines are laid off vertically and horizontally along center lines drawn in these directions through the center of the paper. These distances are marked once only. The T square and triangles are depended upon for accurate lines. OL ct, Cutting fines bb, border > cc, working \ \ FIG. 69. Legend, Lettering, Scale, etc, The legend refers to the description of the drawing, with the scale and the name of the GENERAL DIRECTIONS. 77 one who made the drawing. All these records are placed in the lower right-hand (S. E.) corner of the drawing inside the working edge, and space must be left for them when calculat- ing on the best arrangement of the different views. This generally leaves a blank space along the upper right-hand edge of the paper, but the effect of the drawing as a work of art is sacrificed to utility. As drawings are stored in drawers and it must be possible rapidly to find the one sought, the descrip- tions must be in the same place in all, and they must be at one of the lower corners, so that it may be possible to read them without pulling out each sheet. By raising the right- hand corners of a number of drawings, the legends may be rapidly looked at and the one desired found with the least loss of time. In the S. E. corner is placed the general description of the drawing or drawings on the board. If a number of objects are shown, find as generic a name as possible for them all, but one that will leave no uncertainty as to what may be on the draw- ing. Besides the very general description in the S. E. corner, place near (under, if convenient) each different drawing any especial remarks that may be necessary to more thoroughly describe it. When drawings are made from brass models, after the name of the object the legend reads : ' 4 Sketched and drawn from models." When drawings are made from portions of machinery, after the name of the object the legend reads : * ' Sketched and drawn from work. When drawings are made from blue-prints of general arrangements, first give the name of the ship (Battleship Iowa, Cruiser Detroit, U. S. S. Adams, etc.), then the description of the object or objects ; after that the legend reads : ' ' Taken from blue-print of General Arrangement of Machinery. " If all the drawings on the sheet are taken from the same work, the legend in the S. E. corner may contain the re- MECHANICAL DRA WING. u z o I LQ Q_ U DC 13 CO CD U CC Q_ I CJ X NO V fc g GENERAL DIRECTIONS. 79 marks showing whence the material for the drawing came; in case the drawings are from different sources, the special re- marks are placed near the different drawings. In the legend, the sequence of the different portions is as follows : Name of object represented. Special remarks. Scale. Name. Class. Date. The name of the object is made in some type of heavy lettering and is the prominent part of the legend. When a ship's name or number is given, this is equally prominent. All the rest of the lettering is done with a writing-pen, the letters small and clear. The name is not prominent and is an autograph. Block Letters. This is the type of lettering preferred for heavy type. The letters, as a rule, are three spaces wide and all are five spaces high, as shown in the sketch, while one space separates the letters. The letters M and W occupy re- spectively four and five spaces, as shown. The peculiarity of the letter K is shown. The peculiarities of the figures are also shown. Numerous variations of these letters may be made by vary- ing the heights, widths, slopes, etc., of the spaces; by making solid or skeleton letters ; by drawing shade lines ; by drawing the shade lines only; by shading in any direction and to any extent, etc. Sample drawings of these letters are found in the drawing- room. When block lettering is to be used, measure the length of space that is available and draw a vertical center line. Make a rough copy of the letters to go on one line on a spare piece of paper. Allow the spaces between the words and place 8o MECHANICAL DRAWING. 1 ^M? i^*j-^ ^ "4 -^ > 3 L '. ,. ^-r- :?fc=: 3^ -- \ iEs ZJ^-^H-" ^-i---r^r" \^ ^ / 1 / ^ \ 2 2 / s/ / ^ \ 2 / \^ / \ \ ^ '*'-*' ^ GENERAL DIRECTIONS. 81 82 MECHANICAL DRA WING. figures over each letter and the following space for the number of the spaces actually needed. Half the sum of these figures gives the part of the lettering to coincide with the center line drawn. From the half- width of the space available and the half-number of spaces required, the width of one space is cal- culated. The next smaller division on a regular scale may be used and the spaces laid off from the triangular scale ; or the exact width desired may be obtained very closely and this dis- tance laid off with the bow spacers on a line just below the one for the bottom of the letters. The vertical lines for the spaces may then be drawn and the height chosen for the ver- tical spaces. For ordinary work letters need not be over half an inch high, and three-eighths of an inch is amply large for most drawings. / \ 1 c -U s 1 r> ) L ? 1 1 ^ sr^- 1 rr t '; - Fr^rl i T ] /"\ -4 ^ 1 i i \ \ \ \ \ \ \ \ / \ A / s V / S, / / 4- \ \\ \\X. \\ v V / \ / sr \ \\ V\ ^ T ! T i ll i V \\ A \\ // // // / I yl i / / _*^ / / f jf f J s / /^ s / / / It*^' { / I 1 11 i / // /' // / Another type of block letters is shown. In this case, decide on the total w r idth allowable for each letter and its fol- lowing space, and lay off these total spaces ; then decide on how much of these total spaces shall be letter and how much distances between letters. Divide the laid-off spaces accord- ingly. Draw horizontal lines for determining the beginnings of the slopes at any desired distances from the top, middle, GENERAL DIRECTIONS. 83 and bottom lines. Where these lines cut the vertical bounding lines of the letters the angular lines begin. The slopes may be varied, the slopes made arcs, and the slant of the lines may be changed as desired, but for ordinary drawings the simple type is best. These letters are generally drawn with an opening of the pen that will ensure a good line that may be continued indefinitely and that is at the same time quite heavy. Frec-Jiand Lettering. There are many types of free-hand lettering, but the simplest and most clear and the easiest made are the best. No time should be wasted on the lettering, but it must be distinct. The samples given are very satisfactory and are much used. A little practice brings a fair proficiency. It is well to draw the top and bottom guide-lines for the capi- tals as well as the small letters. The height of the small letters is about y%" , and of the capitals y i6 ". The figures are the same height as the capitals. Variation may be made in the slope of the letters and indi- vidual designs used to a certain extent, but the simpler and more upright the letter the better. Use an ordinary writing-pen. Try many kinds until the most satisfactory result is obtained. Always make the letters and figures distinct. After the drawings of brass models are completed, the different views are no longer marked " Plan," " Front Eleva- tion," etc., as it is supposed that all are familiar with the dif- ferent views by that time. Scales. The scale of the drawing is clearly stated. If only one scale is used throughout the drawing, this scale is given in the legend. If different scales are used in different parts of the drawing, the various scales are placed near the drawings where used, generally under them, so that there may be no possibility of error. MECHANICAL DRA WING. of 1300 LH.P. Vessel* 12345G7890 AB CDEFGHIJKLM a b cdefc/hijkl/m NOPQRSTUVWXYZ &. n op cfT s i u vwxy z . 1234567890 A B C D E FGHIJ K LM a,b ode F a h, ij k i m, n, o NOPQRSTUVWXYZ&. p cj r s i; u, v w x y z , I 2 345678 90 Compressed Type of Lettering GENERAL DIRECTIONS. 85 Scales are stated as follows: Scale, 3" = i foot; y" = i foot; etc. Scales other than those on the triangular scale are stated : Scale, full size; scale, half size; scale, three-quarter size; scale, double size. Never state: Scale, ^ size. Always write out the frac- tion. Never state: Scale, 9" = i foot; or, Scale, 8" = i foot; as there are no such scales on the triangular scales used. Line Shading and Tinting. Line shading and tinting are used for ornamental drawings, and to show more clearly to those not familiar \vith mechanical drawing the intention of the views and the arrangement of the different parts of the mechanism. As shown by the title, the surfaces are covered with lines or tints of different light effects to show as clearly as possible how the object really appears. Line Shading. There are certain prevailing methods of shading surfaces, and these methods apply to all views of an object. The light is supposed to come from the same point as under "Shade Lines," that is, from the N. W. direction and from an angle of 45 above the drawing-board. Flat Surfaces. Fig. 70 shows two positions of half of a hexagonal prism with a smaller hexagonal prism cut out centrally. These views give some of the various types of flat surfaces to be considered. Flat surfaces parallel to the paper and on which the light falls have a uniform light effect, as surfaces A. Flat surfaces parallel to the paper and on which the light does not fall have a uniform dark effect. Flat surfaces on which the light falls and which are inclined to the paper have a light effect which gradually becomes darker as the surface recedes, as surfaces B. 86 MECHANICAL DRA WING. Flat surfaces on which the light does not fall and which are inclined to the paper have a dark effect that gradually becomes lighter as the surface recedes, as surfaces C. Generally speaking, striking contrasts are made at the front of the drawing : the parts near the eye are in high light and A C B A FIG. 70. deep shades, while those parts in the background have less contrast as they are farther away, the parts in the light being less bright, and those in the shade less dark. To SJiade a Cylinder. -In order to produce the rounded effect of the cylinder, lines or tints are graded from light effect to darker ones. The heaviest part of the shade is theo- retically at the position of 45, as shown in Fig. 71. The point of lightest effect is theoretically at a position of 22^, as shown. It is not deemed necessary to study the reason for these points of light and shade. After these points are determined, it is in accordance with the best practice to move these posi- tions somewhat in order to produce a better effect. The darkest part is moved nearer to the central line of the figure, and the lightest part is moved farther away from this center. GENERAL DIRECTIONS. 8? The amount of this movement is proportional entirely, and Fig. 7 1 gives about the right amount. After finally establishing the dark and light lines, one method of line shading is shown in the above figure. In this case all the lines are of the same breadth, and the effect of rounding is produced entirely by varying the distances apart of the lines. A clear line, com- FIG. 71. paratively fine, is chosen and the lines are drawn in succession from one side to the other, the gradations of space being made according to judgment. It seems best to begin at the side of the cylinder nearest to the lightest line, and to follow along to the other. The effect at the edges should be exactly the same. Fig. 72 shows the more ornamental and effective kind of line shading. This is more extensively used also. The dark and light portions are established as before, and the rounding effect is produced by a combination of varying the width of the lines and also the distances apart. Often three or four of the darkest lines at the darkest point of the shading are combined in one. It seems best to begin this shading on the left side that nearest to the lighter portion. The line first drawn should be well chosen and in accordance with the size of the cylinder. This line will establish the weights of the other lines and practically whether the cylinder will be shaded dark or light. After the first line, the others are varied .88 MECHANICAL DRA WING. ;according to judgment. At times three or four lines of the same width are drawn, the spaces between them slightly varied. The combination of varying the width of the lines and the width of the spaces gives a good chance to round the FIG. 72. cylinder up nicely. light effect near the edg At the end, note that there is always a e last finished. There is a slightly wider space left between the last two lines and the others just drawn. This produces the effect of a light streak just near the edge. This is supposed to be the effect of reflected or diffused light coming around the side of the cylinder. This effect is never shown at the other side of the cylinder; the shading there is gradual to the very edge. GENERAL DIRECTIONS. 8 9 Interior of a Hollow Cylinder. As shown in Fig. 73, the heavy part of the shading commences at the edge in shadow FIG. 73. and grades to the lightest part, found as before; then the shading continues to the other side gradually. A Cone. The dark and light points are established as in the case of the cylinder and the same system is followed. In the heavy type of shading each of the shade lines becomes a triangle. The light effect at the side nearest to the heavy 9 o MECHANICAL DRAWING. FIG. 74- shade lines is preserved as in the case of the cylinder. It is j. found advisable in shading the cone to draw the lines from the GENERAL DIRECTIONS. 9! apex and to begin at the heaviest shading, working both ways. Many lines are not begun at the apex but a little below, to avoid a blot. When all the lines are drawn, the light spaces near the apex are filled in with a fine opening of pen. A Sphere. The darkest and lightest points are on the 45 line as shown, and their approximate radial positions determined by eye. See Fig. 75. These lines are drawn as shown under "Shade Lines." A horn center should be used. FIG. 76. 9 2 MECHANICAL DRAWING. Another method. (Fig. 76.) This does not produce the true effect, as the varying lights traverse the surface in zones, but it is much easier to make and is much used. The center of the arcs is the center of the lightest portion. Tinting. The same methods of arranging the lights and shadows of the shading apply to the tinting. Tinting may be done with any colors or with Indian ink. Colors are seldom used ; and as the same methods apply, the description of the method of using Indian ink will answer. Use stick Indian ink not the ink mixed in bottles. The paper must be stretched on the board if tinting is to be done. The drawing must be kept as clean as possible, and the rubber not used, as it roughens the surface of the paper. The tinting is done after the black lines of the drawing are completed without shade lines. The drawing is then washed in running water not rubbed and is allowed to dry. To Prepare the Tint. At least two brushes are needed; two beakers or water-glasses partly filled with clean water ; an ink-slab or saucer in which to mix the ink ; a stick of Indian ink; and a piece of blotting-paper. Clean all these articles thoroughly. Decide on the amount of liquid ink necessary according to the quantity of surface to be covered. Place sufficient water in the ink-saucer and pro- ceed to grind the ink in the water by rubbing it about with a certain pressure on the bottom of the saucer. This requires considerable time, as the ink dissolves slowly. It should be ground until a line made with it by the R. L. pen remains black when dry. This ink is now in condition to be used for drawing. As the ink used in tinting is very much lighter in color, the ink mixed will serve to cover from three to four times the surface that it would cover if used in its black state. In one of the water-glasses or beakers place a small quantity of water ; dip the brush in the top of the mixed ink, so as to take up only the clear ink and leave the sediment, and stir this color GENERAL DIRECTIONS. 93 into the water in the beaker. With a brush test the color of the tint on a piece of drawing-paper, allowing the color to dry. Add black ink until the tint is as desired. The tint chosen should be much lighter than will be the final effect on the drawing, as it is very easy to darken the drawing by laying on another tint, while it is very difficult to repair work that is too dark. Take a clean brush and clean water and carefully go over the surface to be tinted with this water ; be particularly careful that the edges are moist to the boundary lines and that these are not passed, as the tint will follow all these defects. To Lay on a Flat Tint. This seems easy but is extremely difficult, and methods differ also. Some leave the drawing- board level and others tip it slightly, so that the bottom of the board is three inches or more lower than the top. Draftsmen follow the methods that suit them best. The same general plan is followed in either case, only that it is thought that when the board is tipped the tint flows by gravity and assists the operation. However, as it is difficult to tip the board in all the directions required in making a complicated drawing, it is well to learn to tint with the board horizontal. After a space has been moistened slightly with the clean water, dip a brush deeply into the prepared tint and stir it well around so that it is permeated with the same shade of color ; either keep the brush full for a large surface, or for a small one remove part of the liquid by rubbing the brush on the edge of the glass; according to the shape of the surface, carry the brush along one line rapidly and carefully; before this has a chance to dry, run the brush again along in the same direction but a little farther on from the edge, thus making the surface moistened twice as wide as before ; continue in this way, never allowing an edge to dry until the whole surface has been covered; at the end, if there is too much of the tint on the paper, quickly dry the brush by rubbing it on a piece of blotting-paper and then use it to dry up the last part of the 94 MECHANICAL DRAWING. work. If carefully done, it will be found that a perfectly even coat of color has been placed on the surface. If this tint is not dark enough, it maybe darkened by successive tintings; but never put on a second tint until the first one is "hand dry," or dry to the touch. Never try to touch up a small portion of the surface except by " stippling, ' ' which alters the entire effect of the work. When using the brush along the boundary lines of the space, always keep the point of the brush towards the edge. Do not bear on the brush, as this may cause marks to be made that will show under the tint. For large surfaces lay on a light tint. Reverse the board and lay on a second one. Turn the board and repeat from one side; then do the same from the other side. This does away with the effects of streaks in any one direction, and the result is an even tint over the whole surface. Graduated Tints. There are two general methods, the French and the American. The French method consists in dividing up the space to be covered into small rectangles (these must not be marked with pencil, as the marks cannot be eradicated) ; putting on a tint in the rectangle to be darkest and allowing it to dry; putting on a tint covering the rectangle already tinted and an adjacent one and allowing it to dry again ; and continuing this operation until the entire surface is covered. By this method the shading is in streaks that are more or less prominent according to the width or narrowness of the rectangles. This method takes too much time also. The American method is most used and takes less time, while the effect is equally good. This is called the method of shading by softened tints. For a surface that is flat and inclined at an angle to the paper, the method is as follows : Saturate the brush as before with the tint and remove most of it against the side of the beaker ; lay a narrow line of the tint along the line of darkest shade ; while this is still wet dip GENERAL DIRECTIONS. 95 FIG. 77- FIG. 78. FIG. 79. FIG. 80. 9 6 MECHANICAL DRA WING. FIG. FiG. 82. GENERAL DIRECTIONS. 97 the point of the brush in clean water, which dilutes the color on the brush, and apply a line along the edge of the tint previously laid on, rubbing into the edge of the other tint; again weaken the tint and continue as before. Each operation leaves a lighter tint, and at the end a clean brush in clear water leaves practically no color. This method softens the grada- tions from one tint to another and is rapidly finished. When the surface is dry the operation may be repeated and thus continued until the desired effect is produced. For large surfaces it is well to mix three or more tints of varying darkness. After laying on the first line of the darkest tint, dip the brush in the next darkest and so carry on the shading until approaching the light edge, when finish with a clean brush and clear water. In shading cylinders, cones, and spheres, the work is done very rapidly, as the dark tint is first laid in the interior of the surface and the shading must be carried away from the edges of this first tint in all directions before any of it may become dry. Stippling. When the work is uneven, as is often the case, due to irregularities in the paper and lack of experience, stippling may be resorted to to improve the effect. Fill the brush with a light tint and remove most of the color; touch the lighter portions of the tinting with the point of the brush until the surface is brought to the right effect by these points of color. After stippling, it is well to go over the whole sur- face with an even light tint to smooth down the effect. Many draftsmen stipple a drawing after the shading is complete, as it is thought to improve the effect. Tracing. If more than one copy of a drawing is required, it is traced, and blue-prints are made from the tracing. The business method is to make the original drawing in pencil only; this is traced in ink, and the tracing is kept as the original. The pencilled drawing is not retained. Tracing-cloth or paper is transparent; it is tacked in place 98 MECHANICAL DRAWING. over the drawing as described under 4< Thumb-tacks," and the method of tracing follows the method of inking the original drawing as described under " Plan of Procedure. " Tracings are made on the smooth or shiny side of the paper. As there is sometimes trouble in getting the ink to run freely on the tracing-cloth, special powders are furnished ; dust on a little powder and rub it around with a cloth. Electro-silicon is found to be an excellent powder for this pur- pose. A blackboard-eraser saturated with chalk is sometimes rubbed gently across the paper for the same purpose and answers as well. The tracing is completed, lettering, border lines, legend, etc. It is then removed from the board and trimmed, and blue- prints are made. Be careful not to wet the tracing. Errors should be erased only with the rubber ink-eraser. After that, rub the surface with a soapstone pencil and polish with agate or other hard substance. Blue-printing. The tracing is placed in the printing- frame, the shiny or drawing side next the glass ; the sensitive paper is placed next the tracing, the sensitive side towards the tracing ; the backing is put in place and the frame placed so that the sun's rays strike normally. Ordinarily in from five to ten minutes the print is completed. The print is removed from the frame in as dark a place as is convenient, and is then placed face down in a bath containing clear, running water sufficiently deep to cover the paper well. The print is moved about occasionally and remains in the water about fifteen minutes. The action is made more rapid by placing a small quantity of ordinary salt in the water. The print is now dried, preferably by being tacked at the upper edge so as to hang vertically. In this way it does not become curled and troublesome. These blue-prints are now the working drawings used, as GENERAL DIRECTIONS. 99 many copies may be furnished; the original, the tracing, is carefully preserved. . Line shading may be very well done on tracing-cloth, but the tinting draws the cloth out of shape as the tint dries. So, instead of tinting, colored chalk is rubbed on the back of the tracing. The same light and dark effects may be produced as with tinting, and the blue-print carefully reproduces these effects. To write on a blue-print (white characters), or to scratch out or wipe out any portion that has been printed, use a saturated solution of sal-soda (washing-soda). If the blue print is underexposed, it may be developed by acetic or hydrochloric acid bath. The ordinary blue-print consists of white lines on a blue ground. Many prefer blue or black lines on a white ground. This is accomplished by printing from the tracing on special paper a "negative " which consists of white lines on a black ground. By using this " negative " instead of the tracing, a print of either blue or black lines on a white ground may be produced. Sketches. Sketches are considered one of the most impor- tant parts of the course. They are made in the sketch-books, free-hand, not to scale. The attempt is made to sketch as well as possible an accurate representation of an object in the different views needed, and to preserve quite accurately the relative proportions of the object. Dimensions are carefully taken with calipers and rule only and are clearly marked on the sketches. The idea to bear in mind when making sketches is that there will be no further opportunity to see the object after once the sketch is completed ; it is supposed that the one making the sketch is on detached duty and must make a sketch so accurate that he will be able to make a working drawing of the object at any later date. No instruments whatever are used in making the sketches. 100 MECHANICAL DRA WING. The pencil used is softer than HHHHHH and is sharpened to a point, and should be kept fairly sharp if good work is attempted. The first sketches are made on the lined paper in the front part of the sketch-book. This assists in learning how to make straight lines free-hand, and also assists in drawing lines per- pendicular to each other and in preserving the general propor- tions of the sketches. After the drawing of the brass models is completed, sketches are made on the unlined paper in the other parts of the book, as it is considered that all may have acquired sufficient ability by that time, and the lined paper may not always be at hand. The sizes of the sketches are not in proportion to the size of the object sketched, but are large enough so that all details may be shown without confusion and so that all dimensions may be readily placed and clearly read. As a rule, the same views are made in sketcning as are made on the drawing-board, and the same dimensions that are placed on the sketch are eventually placed on the drawing. In the sketch, however, there are many abbreviations and lessenings of work. It is sufficient to represent a portion of the work. If a large surface is to be hatched, in the sketch only a small portion need be hatched, as it is understood that the remainder must be treated in the same manner. If there are a number of threads or bolt-holes of the same kind, it is sufficient to sketch one of them carefully and indicate the number and positions of the others. The first thing to do when beginning a sketch is to ex- amine the object and decide what sketches are required and then decide in what order to make them. If the book is suffi- ciently large, the general plan is followed and the points are projected from one drawing to the other. The projecting lines are not drawn. There may be a choice as to which one is drawn first. It may be the Plan, the Side Elevation, or the Front Elevation, but it is best to draw first the one that gives GENERAL DIRECTIONS. IOI the best general idea of the object and the most points to project from. After the views are decided upon, next draw the center lines. Then the sketch continues according to the ideas of the sketcher. The sketches are made quickly, a free sweep of the hand for the lines and a rapid proportioning by eye of the parts. After the sketches are completed, the arrow-points are placed on the sketches for the ends of the dimension lines. Cover the sketches with these arrows, deciding quickly what dimensions are needed. Then draw rapidly the dimension lines, leaving the spaces for the dimensions. Then make the measurements quickly and accurately and place them on the sketch. In this way the work goes on systematically and quickly. After completing the sketch, go over it with the idea of noting whether the object could be constructed from the notes taken and the sketch made. Write on the sketch the kinds of metals used in the different parts, unless these are shown by the symbolic hatching. Note if any of the bolts or nuts differ from the standard. Note what parts of the object are finished, and so state on the sketch. If the object is finished all over, note on the sketch, " Finished all over." If a complicated machine is to be sketched, first make a free-hand sketch of the general outline, omitting all lesser details, but take special care to get the exact positions of the principal centers in all views. After the general view is sketched, the details may be drawn one by one. The sketches must not be overcrowded with details. From the dimensioned sketches the scale drawings are made. The scale of the drawing is decided upon, bearing in mind a correct and neat arrangement of the required views and the space for the legend. Fig. 83 is a sample of sketching when the lined paper is used. It is seen that two views, part of one in section, are all 102 MECHANICAL DRAWING. that are needed for a thorough representation of the object. The section shows the material to be cast iron. Ffir is ti -1 . FIG. 83. Plan of Procedure in Making a Drawing. After the paper is stretched or tacked on the board and is ready for use, the following is the sequence of the different operations in making the drawing and blue-print (if required). 1. Examine the object to be drawn, and decide what views are necessary so that it may be properly represented. 2. Make dimensioned sketches. 3. Center the drawing-paper. 4. Mark the working, border, and cutting lines in pencil. ^. Decide on the scale to be used. 6. Establish the positions of the center lines and pencil them in carefully. (Special directions are given for the first GENERAL DIRECTIONS. 1 03 drawings or sheets, so that from this point the methods may vary slightly; but the same general plan is followed.) 7. Inspection of the drawing. 8. Pencil the drawing. 9. Inspection. 10. Ink the drawing in black ink: no sections, no tinting, no shade lines. 11. Inspection. 12. Tint or line shade, if required. 13. Inspection. 14. Draw center lines in red ink. 15. Draw extension and dimension lines in red ink. 1 6. Make the dimension figures and arrows in black ink. 17. Inspection. 1 8. Hatch sections. 19. Inspection. 20. Draw shade lines. 21. Inspection. 22. Make the legends and other lettering in black ink. 23. Draw the border lines in black ink. 24. Clean the paper. 25. Inspection. 26. Trace drawing. (If required.) 27. Inspection of tracing. 28. Remove and trim tracing, and cut the drawing from the board. 29. Make blue-prints. 30. Stretch paper for the next drawing. Remarks on the above: Before beginning any operation, read the remarks under that head. Pencilling the Drawings. Read carefully the remarks under " Pencils." Note carefully the remarks under " Center Lines" and carefully make all measurements from them as far as possible. Lay off first all center lines for portions of drawings. 104 MECHANICAL DRAWING. When straight lines are joined by arcs in pencil-work, the straight lines are generally drawn first and centers of the arcs found and the arcs drawn so as to be tangent to the lines. The methods given in Geometry generally cover all cases. When inking, the reverse method is followed, as the centers are already found ; these centers should be made distinct in the pencilling, so that they may be readily found when inking. Make no shade lines in pencil-work. Do no hatching in pencil-work. When a large number of lines radiate from a point, draw the outer lines to the point and stop all the others at a distance of from y" to YZ" away. Leave no centers to be found when inking, and leave no lines to be " faired." The pencil-work must be complete except for shade lines, hatching, dimensions, and tinting. Plan of Procedure in Inking. Ink all the arcs on the board first, beginning with the largest; then ink all the irreg- ular curve lines; then the straight lines. Always draw the straight lines from the curves if possible never towards them. After finishing the arcs and irregular curves, use the tri- angles, beginning at the top of the board. Place the T square so that the triangle laid in place will reach just above the highest lines on the board. Beginning at the left sweep across the board with the triangle and draw the vertical lines found at any part of any one of the drawings or views. Then lower the T square and again sweep across with the triangle ; and so on until all the vertical lines on the board are completed. The horizontal lines are drawn by means of the T square, beginning at the top of the board and sweeping the T square from top to bottom, drawing lines as they appear above the T square at any part of the board. Read carefully the remarks under " R. L. Pen." If the drawing is to be tinted or covered with line shading, note carefully the remarks under these headings, and take care not to draw a heavy line until the drawing has been washed. GENERAL DIRECTIONS. IO$ In shading the circles, follow the method as in drawing them; shade the large ones first, then the smaller ones, etc. Read carefully the remarks under " Shade Lines." General Remarks. Note always and continually the direc- tion from which the light should come. Keep the instruments clean. Clean them at once when through using them. Keep the instruments not in use off the drawing-board. Keep the paper clean. Come to the drawing-room with clean hands, and clean them often while drawing, if necessary. Cover the portions of the drawing not being worked upon with paper or cloth to keep them clean and the lines clear. Never do free-hand work that may be done with the instru- ments. Even " breaks " and " tails " may be made best with instruments. The excellence of the work is of far more importance than speed. It is better to make one good drawing than a dozen poor ones. Speed combined with excellent work is the object aimed at, but the speed must come last. Pens that are dull, or instruments requiring repairs, may be turned in to the desk. It is advisable, however, for all to learn to sharpen their own pens. When compass pens require sharpening, turn in the whole instrument, so the sharpening may be tested. Pens that are found to be soft may be turned in for retem- pering. Attach to the instruments turned in a slip of paper giving name, class, and repairs needed. Write the names clearly on the covering cloths and on all triangular scales, irregular curves, etc. Write the names clearly in ink on the N. W. corner of the drawing-paper outside the border line. Bring all models to the middle of the room at the end of the period. FIRST DRAWINGS. THESE consist of three sheets. Sheets I and II are for the purpose of teaching the use of the instruments ; Sheet III is a study of Projection and Working Drawings. In Sheets I and II there are eighteen figures. Each figure represents a block raised above the drawing-board. Some of the figures show lines drawn on the upper surface of the blocks, and some show other figures resting on the top of the original one. The figures in these two sheets are all "Plans." The remaining portion of the sheets is for the "Legend." Every scale on the triangular scale is used in each of these sheets. Sheet I consists of straight lines only. The attempt is made to bring into this sheet all kinds of straight-line work. Sheet II consists of arcs; combinations of arcs and straight lines ; combinations of arcs with other arcs and with irregular curves; irregular curves. The attempt is made to bring into this sheet all kinds of curved-line work. A A FIG. 1 T "m 4 <-- 3-- SCALE. SCALE. s to 00 ft 21" >i ^ V GENERAL VIEW OF SHEETS I AND II. 106 FIRST DRA WINGS. IO/ Sheet III consists of drawings of brass models. Three views are made of each model and the points are all projected. The models are cut across in certain planes and are pinned together. They may be separated at the planes, and sections studied and drawn. They are then hatched with Standard Hatching. The figure on p. 1 06 shows the dimensions of the Working, Border, and Cutting Lines used in all drawings. It also gives the dimensions of the figures in Sheets I and II. SHEET I. As stated under " Working, Border, and Cutting Lines,'* center the drawing-paper and draw the lines. Measure once only for these lines and carry the lines across from these measurements. The T square and triangles are depended upon for the rectitude of the lines. On the first ruled page of the sketch-book make a sketch of the general view of the sheet, placing there the dimensions of the bounding lines of the paper and of the figures of the sheet. Full directions should be given with the sketch so that the outlines may be drawn from it. This should occupy only about one-fourth of a page in the sketch-book, leaving room for some of the figures. Mark off to "full-size scale " the boundaries of the different figures of the sheet. Measure along the center lines and draw carefully. One measurement only should be made for each line, and the lines should be carried across the board. The outer lines of the figures coincide with the working lines of the paper. Sketch each figure in the sketch-book before putting it on the drawing-board. The text-book is kept closed and the work is done entirely from the sketch-book. The text-book is to be used only for correcting the sketch. Pencil-work. Place Fig. I in the upper left-hand corner; . -;_" ...i',"? ;" ^-^ t 108 MECHANICAL DRAWING. continue on to the right along the upper row of figures ; begin again at the left hand of the second row and continue as before to the right; leave the legend until all the figures are inked. Finish completely all the figures in pencil before inking any figure. When a line of figures is completed cover it with paper. Pencil-lines cannot be made too fine, provided they are clear-cut and distinct. See notes under "Pencils and Pencil- ling." When the pencil-work of all the figures of the drawing is completed, the drawing must be inspected before the next step is begun. Put no dimensions in pencil on the drawing. Ink-work. In inking, do not make too fine lines. Follow the directions under "Use of the R. L. Pen." For this sheet disregard the general instructions for inking drawings, and ink each figure in fine lines in its order as pencilled, but ink none until all the pencil-work is completed. When inking the drawing, make all the lines of the same figure and of the same type of the same width. Set the pen before drawing the first line, and draw a sample line on the margin of the paper beyond the cutting line, taking care to draw this line by guiding the pen against the T square or tri- angle. Often test the pen by drawing a line near the sample line for comparison. When all. the figures are inked, the drawing must be inspected before the next step is begun. After the first black lines are inspected, the center lines, dimension lines, dimension projection lines, arrows, and figures are completed according to the directions given under the proper headings. The red-ink lines are made as fine as possible. Another inspection of the drawing follows. After the red-ink work is inspected, draw the shade or relief lines on the right-hand and lower sides of the figures and on the other parts as required. Make these lines' about four FIRST DRAWINGS. 109 times as heavy as the other parts of the drawing. These lines are drawn over the lines previously drawn, but the extra width of line is outside of the original lines. All these shade lines are of the same width throughout the sheet, and they must not be too heavy. The pen is opened the right amount, and the line made with one sweep. In drawing these shade lines, draw the vertical ones first. Another inspection of the drawing is made after the shade lines are completed. After the shade lines are inspected, the legend is placed in the space reserved for it. Lines are drawn in pencil at the proper distances apart and the block letters are laid off Care must be taken to calculate the spaces occupied by the letters so as to have the letters central in the space left for the pur- pose. See notes under "Lettering." The lettering of the free-hand type is next made, the name written, and then an inspection follows. Scales are marked as stated under " Triangular Scale." After this inspection, the border lines are drawn and the drawing cleaned. A final inspection follows, and then the drawing is cut from the board. Paper is stretched for the next drawing. 7 \- :*- J- "n\x SHEET I. FIG. 1. Scale, full size. (Use 16 scale.) Horizontal full lines. no MECHANICAL DRAWING. T square ; triangular scale ; full lines, pencil and ink. Pencil-work. Measure off the vertical distances as given and mark the points with the bow spacer or compass-points. Draw lines across at all marked points. Sweep the lines across in pencil from left to right, not at- tempting to begin or stop the lines exactly at the boundary lines. Ink-work. The lines are full lines of equal width. Each line must be clear, the nibs of the pen cutting sharply. The endeavor is to make the lines exactly alike, equal in width and distinctness. Begin the lines firmly, and carry them on with an even pressure, and stop them exactly at the boundary line. Do not draw the dimension lines until all the figures are completed. See notes under "Dimension Lines." St, * -it 1 1 1 1 f _, |"^ j%| SHEET I. FIG. 2. Scale, full size. (Use 16 scale.) Vertical broken lines. T square; triangular scale; triangles; full lines in pencil, broken lines in ink. Fig. 2 is the same as Fig. i turned through 90. The pencilling is done as before, full lines drawn from FIRST DRA WINGS. Ill bottom to top and using either triangle, sliding it along the T square and noting that the lines are drawn from bottom to top and on the left side of the triangle. When inked, the lines are drawn as broken lines. The lengths of the dashes and spaces are estimated by eye, not measured. The lines to the left are made with dashes about y 2 " long, and the spaces are about y%" wide. The dashes and spaces of successive lines break joints with each other irregularly. The next lines to the right are made with dashes about y^" long, and the spaces are about T V wide. The next lines to the right are made with dashes about y%" long, and the spaces are about -}$" wide. The next lines to the right are made with dashes about T y" long, and the spaces are about l " wide. In drawing these lines the endeavor is to make the lengths of lines and widths of spaces of each set of lines as uniform as possible, and to make each line exactly as wide and as promi- nent as the others. SHEET I. FIG. 3. Scale, 3" = i foot, or one-fourth size. Horizontal heavy lines. 112 MECHANICAL DRAWING. T square ; triangular scale ; full lines of varying widths when inked. Pencil-work. From one of the top corners measure down- ward the following distances, each distance measured from the corner: #"; #"; #"; itf"5 '#"; 2#"5 3#' '; 4#" '\ $W\ 6 7 /s"] %%"', 9Y"\ n#". The remaining distance is y%", which is a check. Draw a vertical center line and horizontal lines through each of the points marked. Ink-work. Draw the boundary lines and the lines through the marked points. These lines are fine lines. Shade the right halves of the lines as in the figure. The top line is the fine line already drawn. Make each line in succession heavier than the preceding line. Place the extra width of the lines entirely below the lines already drawn. For the method of drawing these lines see ' ' Shade Lines. ' ' Do not draw the heavy lines to the boundaries. After all are drawn, place the triangle vertically and fill in the spaces left with a fine opening of pen. Beginning with the sixth line from the top, for a length of 2" on the left ends of the lines make lines that correspond in total width to those on the right, but leave a narrow strip of white along the middle of the width. This is the effect used in boiler and ship-building work to show that two plates are together at the line of demarkation. Make the edges sharp with a fine opening of pen, and fill in with a coarse opening of pen. The center line is drawn when the red-ink work is done. FIRST DRAWINGS. SHEET I. FIG. 4. Scale 10. Inches divided into tenths. Vertical heavy lines. T square ; triangular scale ; triangle ; full lines, of varying widths when inked. Pencil-work. From one of the top corners lay off hori- zontally the following distances, each distance measured from the corner: '.'075; '.'225; '/45O; ".7$ ; i'/i25; i'/575; 2 / /io; 2'/625. The remaining distance is "375 for a check. Draw a horizontal center line and vertical lines through each of the points marked. Ink-ivork. Draw the boundary lines and the lines through the marked points. These lines are fine lines. Make the upper halves of the lines of increasing width, as in Figs. 3 and 4. The left boundary line is the fine line already drawn. Place the extra width of the lines entirely beyond the original lines from the original point of measurement. Beginning with the sixth line from the left, for a length of '.'5 from the bottom draw lines as wide as for the upper half of the figure, but leave a narrow central strip of white. These heavy lines will have to be squared at the ends by using the R. L. pen along the T square. 114 MECHANICAL DRAWING. The right-hand and lower boundaries of the figure are shaded. The center line is drawn when the red-ink work is done. SHEET I. FIG. 5. Scale, 2" = i foot, or one-sixth size. 45 triangle. T square ; triangular scale ; triangle ; full lines, of varying widths when inked. Pencil-work. Draw the diagonals. From the N. W. and S. E. corners of the figure measure the following distances on the diagonal towards the center, each distance measured from the corners: #"; #; i#"; 2^"; 3 #"; 5 ^"; 7"; 9"; nj^". The remaining distances are each i^", which is a check. Through these marked points draw lines parallel to the other diagonal of the figure. Ink-work. Draw the boundaries of the figure and the lines through the marked points with a fine pen. Beginning with the lines nearest the corners make half of each successive line heavier than the preceding in about the proportion of Figs. 3 and 4. The two lines nearest to the center are made heavy FIRST DRAWINGS. all the way across. The weight of the lines is towards the center. The diagonal lines are in red ink and are drawn when that kind of inking is done. \ I SHEET I. FIG. 6. Scale, full size. 45 triangle. T square; 45 triangle; full lines in pencil and ink; shade lines. The figure represents blocks resting centrally on each other, the smallest on top. Pencil-work. Center the figure and draw as shown, using only the T square and the 45 triangle. The checks on the work are the inscribed circles, as shown. Ink-work. The lines are all of equal width and distinctness, but fairly heavy. The construction and check lines are drawn in red ink. The blocks are shaded according to remarks under " Shade Lines." Carefully choose a width of line, not too heavy, and do not change the pen when shading. n6 MECHANICAL DRAWING. SHEET I. FIG. 7. Scale, f" = i foot, or one thirty-second size 60 triangle. T square; triangular scale; triangles; full lines of varying widths, pencil and ink; shade lines. The figure represents blocks resting centrally on each other, the smallest on top. Pencil-work, Center the figure with the 45 triangle laid along the T square. With the 60 triangle laid along the T square draw lines making angles of 60 with the horizontal through the center of figure. From the extremities of the horizontal center line draw lines making angles of 60 with the horizontal, and extend them to cut the lines last drawn. Through these intersections draw horizontal lines. This forms a hexagon. Through the central point of the figure draw a line at 30 with the horizontal, and extend it to cut one side of the hexagon. This line will be at right angles to the side of the hexagon. Beginning at the side of the hexagon, measure to scale towards the center of figure along the line last drawn the following distances, each distance measured from the side of the hexagon: 2"; 4"; f'\ ""; 16"; 23"; 2 ft. 5"; 3 ft. i". FIRST DRA WINGS. 117 Through these points draw lines parallel to the side of the hexagon from which the distances were measured. Carry these lines around the figure. They make a number of hexagons within the original hexagon. Portions of circles are drawn with the bow spacers as far as they can be used, and after that with the compasses through the extreme points of each hexagon, as a check. The center of figure is the center from which these circles are drawn. Ink-work. The only black lines are those of the boundaries of the figures and the hexagons. All lines at angles of 60 and 30 that are used in construction, as well as the lines for centering the figure and the vertical and horizontal center lines, are drawn in red ink. The arcs are also in red ink. Place shade lines on the blocks. Take care that the heavy portion is outside the original line. SHEET I. FIG. 8. Scale, " = i foot, or one-sixteenth size 60 triangle. Il8 MECHANICAL DRAWING. T square ; triangular scale ; 60 triangle ; full lines in pencil and ink; shade lines. The figure represents several 60 triangles. Pencil-work. Center the figure and draw the vertical center line; draw lines through the center making 60 with the horizontal. Draw the triangles in position, as shown. The distances between the outer edges and the openings in the triangles is on all sides 3" to the scale given. Checks for the work are circles drawn with the center of figure as a center through the corresponding points of the tri- angles. Ink-work. No construction lines are drawn. After the triangles are drawn, the proper edges are shaded in accordance with directions under " Shade Lines." The vertical center line is extended beyond the figure in red ink. The check circles are fine lines in red ink. FIRST DRAWINGS. SHEET I. FIG. 9. Scale, i" = i foot, or one-twelfth size. 45 triangle. T square; triangular scale; 45 triangle; full lines, pencil and ink; shade lines. Same as Fig. 7, substituting 45 triangle. Width of sides of triangle two and one-quarter inches to scale given. Extend both horizontal and vertical lines beyond the figure in red ink. Check circles are drawn as for Fig. 8. I2O MECHA Nl CA L DRA WING. SHEET I. FIG. 10. Scale, full size. 45 and 60 triangles. T square; triangles; full lines of varying widths, pencil and ink. Pencil-work. Draw the diagonals. With the 45 triangle in position on the T square and the 60 triangle resting against the 45 triangle, draw the figure for all four quadrants. The checks for accuracy are circles drawn with the center of figure as the center and radii for corresponding points. Ink-work. The diagonals and check circles are drawn in red ink. The black-ink lines gradually increase in width from the corners to the center corresponding lines of equal weight. The extra weight of the lines is equally divided on either side of the original line. FIRST DRAWINGS. 121 SHEET I. FIG. 11. Scale, full size. 45 and 60 triangles ; no T square. Triangular scale; 45 and 60 triangles; full lines, pencil and ink. Shade lines. All lines are drawn with triangles only as guides. The figure shows small blocks of equal heights. Those in the center are pushed together. Pencil-work. Draw the diagonals, horizonal and vertical center lines. From each corner measure i" on one side only of the boundary, and from the points marked draw lines perpendicular to the diagonal at the nearest corner. From the extremities of these last drawn lines draw lines within the figure making angles of 30 with them. These lines should meet on the diagonals. Check circles are drawn with the center of figure as a center and radii to the last points found. From the center of figure draw lines on both sides of the diagonals making angles of 30 with them ; this makes four continuous lines through the center. Measure on one of these lines only a distance of ffl 1 '. Begin at the point marked and 122 MECHANICAL DRAWING. complete the figure abed, etc., by drawing lines parallel to the diagonals and to the center lines. The last line drawn should pass exactly through the original point. A check circle is drawn with O as a center and should pass through all these points. From abc, etc., draw lines outside the figure already drawn making angles of 60 with the lines ab, cd, etc., extending these lines to meet the nearest horizontal or vertical center lines. A check circle is drawn through the meeting-points of each pair of these lines. Ink-work. The lines, except check circles, diagonals, and center lines are solid ink-lines made with a fair opening of the pen. All are of equal width. After all the lines are drawn, the figure is shaded according to directions under " Shade Lines." The check circles, diagonals, and center lines are drawn in red ink. SHEET I. FIG. 12. Scale, 4" i foot, or one-third size. 60 triangle. T square ; triangular scale ; 60 triangle ; full lines in pencil, full and broken lines in ink. FIRST DRA IV INGS. 12$ Pencil-work. All lines are full lines. Using the scale given mark off the lines AB and CD into lengths of I " , and the lines A C and BD into lengths as follows : AE = BG = CF = DH = \%" . Divide these lines into spaces y%" long. Divide the lines EF and GH into spaces #" long. From the divisions of AB draw lines at angles of 30 with the T square. From the divisions of CD draw lines at angles of 60 with the T square. The triangles are laid along the T square, and lines are drawn from left to right always. The vertical center line JK is a check on the work. From the divisions of AE, FC, BG, and HD draw lines at angles of 30 with the T square. From the divisions of EF and GH draw lines at angles of 60 with the T square. The horizontal center line LM is a check, as all the inter- sections should be on that line. Ink-work. Draw full lines as fine as the pen will maintain from the divisions of AE and FC to the horizontal center line. Draw broken lines as fine as those above from the divisions of BG and HD to the horizontal center line. Draw full lines from the divisions of GH to the horizontal center line, the lines to be fully twice as broad as the lines previously drawn noting that the lines are made broken where they come in contact with the previously completed full lines. Draw broken lines from the divisions of EF to the horizon- tal center line, the lines to be of the width of those just com- pleted. Draw full lines from the divisions of AB to the vertical center line, the lines to be four times as broad as the lines first drawn. Draw broken lines from the divisions of CD to the vertical center line, the lines to be of the same width as the lines last drawn. I2 4 MECHANICAL DRAWING. The lines JK and LM, the center lines, are drawn in red ink later. X C D\ SHEET I. FIG. 13. Scale, full size. Bow spacers. T square; 45 triangle; bow spacers; full lines in pencil, full and broken lines in ink. Pencil-work. Draw the diagonals. These should check exactly with the 45 triangle laid along the T square. With the bow spacers, space by trial (see " Bow Spacers") each of the half-diagonals into nine parts, and draw full lines through each point parallel to the other diagonal, using the 45 triangle sliding along the T square. For the lines running S. E. and N. W. draw from the N. W. point; for those run- ning N. E. and S. W. draw from the S. W. point. In draw- ing lines parallel to AD, begin with that nearest B\ for lines parallel to CB, begin with that nearest A. Do not take time to begin and stop the lines at the boun- daries. With the bow spacers divide each space of OC and OD into three parts and draw full lines as before. FIRST DRAWINGS. 125 E and F are at five of the original spaces from the center. Divide the spaces of EC and FD into two parts with the bow spacers and draw lines as before. Note that in this figure the lines that are to be broken lines when inked are not drawn broken in the pencil-work. Ink-work. In inking, set the pen for a line that is not the finest that the pen will make, but as fine a line as the pen will maintain and keep the ink running freely without clogging. Draw the lines parallel to AD full lines and those parallel to BC broken lines, varying the lengths of the dashes from %" long for the lines farthest apart to x / l6 " long for those nearest together. SHEET I. FIG. 14. Scale, full size. Dividing lines into parts. T square; triangle; bow spacers; full lines in pencil, full and broken lines of varying widths in ink. Pencil-work. Divide each boundary line of the figure into four, five, or six parts by laying off from each corner any line at a small angle with one of the boundaries of the figure, and spacing off for four, five, or six times any convenient distance 126 MECHANICAL DRAWING. with the bow spacers ; connect the last points marked with the nearest corner as shown, and draw lines from the other points parallel to this line. Use a different distance with the bow spacers in each of the four cases. Connect all the divisions of the side lines with the opposite corners in full lines. Ink-work. The black-ink lines are varied as shown: one set, broken lines ; one, fine full lines ; the other two, full lines of different widths. The construction lines are drawn full in red ink after com- pleting the other lines. x/l '/ SHEET I. FIG. 15. Scale, -|" = i foot, or one twenty-fourth size. Dimension lines and figures. Triangular scale; triangles; full lines in pencil, full and broken lines in ink ; dimension and dimension projecting lines ; dimensions. Pencil-work. Find the middle points of the top and bottom lines of the figure. FIRST DRAWINGS. From the middle point of the bottom line measure in each direction the following successive distances: two of 2"; two of 2%"; two of 3"; two of 3^ // ; two of 4". The remaining distances to the corners should be 6" each for a check. From the middle point of the top line measure in each direction the following successive distances: one of 7%"\ one of 8"; one of 9%"', and one of n". These last dimensions should mark points coinciding with corners of the figure. From the upper corners measure downwards the following suc- cessive distances: 14%"', 12}^"; 10^''; 8^"; 6y 2 " ; $%". The distances from these last measured points to the lower corners should be each 16" for a check. From all the points marked off on the bottom line in sequence draw lines on the same side of the vertical center line to the points marked off on the top and side lines in sequence. Begin at the bottom and lay off on the vertical center line the following successive distances: 22^ ".; 2 ft. 5^"; 20". This last distance should just reach to the top line. Through these points marked on the vertical center line draw lines from all four corners of the figure, and measure to the nearest quarter inch to the given scale the distances from the points where these last lines cut the boundaries of the figure to the nearest corner. These dimensions, when placed on the drawing at the end of the inking, are checks for the accuracy of the last part of the work. Ink-work. Ink the first set of lines with fine full lines ; ink the lines through the points on the vertical center line with fine broken lines, with dashes about Y%" long. The measurements required are placed on the figure after all the figures are completed. Dimension and dimension pro- jecting lines are used. See the notes under " Dimension Lines. ' ' The vertical center line is in black ink to the boundaries of the figure, and extended in red ink about ^" above and below. 128 MECHANICAL DRAWING. SHEET I. FIG. 16. Scale, full size. Section: Hatching. T square ; triangles ; bow spacers ; full lines, pencil and ink ; shade lines ; hatching. The figure represents a horizontal section through a piece of cast iron, the iron resting on the lower block. Pencil-work. Divide one top and one side boundary line into six parts each by drawing lines from a corner at an angle and using the bow spacers and a different spacing length for each. Draw the horizontal and vertical lines, running them entirely across the figure. Do not hatch in pencil. Ink-work. Draw the figure in fairly \vide black-ink lines. Begin at the N. W. corner and hatch the figure with lines at an angle of 45, from S. W. to N. E. The line used for hatching is not the finest the pen may make, but is as fine a line as can be depended upon. Do not fail to make every line of the hatching just as distinct as if it were a line of the figure. FIRST DRAWINGS. I2 9 When a line of the hatching is begun and ends at a space, the same line is continued beyond the space if it would cut the figure farther on. Shade the figure according to remarks under "Shade Lines. " Refer to remarks under " Hatching." The lines used in dividing the boundaries into spacers are inked in red ink. Draw center lines in red ink. SHEET I. FIG. 17. Scale, full size. Line shading. T square; 45 triangle; full lines, pencil and ink; shade lines ; line shading. The figure represents bands of metal interlaced, with line shading for the flat surfaces to make the figure clearer. Pencil-work. As in the preceding figure, divide the sides into six parts; using the 45 triangle draw the intersecting lines as shown, but make them continuous across the figure. Ink-work. Before inking, it is well to make small marks to identify at least one of the longer bands, as, for instance, the 130 MECHANICAL DRAWING. longest one running from N. W. to S. E. With this one clearly marked there should be little trouble in following the figure without error. Draw all the lines at one angle first, then the others. Put shade lines on the edges requiring shading. Line-shade the strips. Those from the N. E. to S. W. shade with light lines, those from N. W. to S. E. with heavier ones. These lines are equally distant apart, and about eight are placed on each strip. The construction lines for dividing the boundaries are inked as full lines in red ink. SHEET I. FIG. 18. Scale, ITJ" = i foot, or one-eighth size. Protractor. Triangular scale; T square; triangles; protractor; full lines in pencil, full and broken lines in ink. Pencil-work. Draw the vertical center line. From the middle point of the bottom line on each side lay off the follow- ing successive distances horizontally: i"; i^"; i^T'; ^y\" \ 2"; 2 The remaining distance is for a cjieck. FIRST DRAWINGS. . 131 Beginning at the top corners, measure off downward on the side boundary lines the following distances, measuring in each case from the top corners: y" '; 3^"; 8^"; n^"; 17^"; 23". The remaining distance on each side is i". Connect the points laid off* on each side from the bottom center with those laid off from both the top corners in succes- sion on each side. Measure the acute angles made by these lines with the bottom line to the nearest quarter degree, or 15 min. See "Protractors." The average of the measurements of the two corresponding angles on the two sides of the center line is marked on one of the angles after finishing all the figures. In order to measure these angles, it is necessary to extend most of the lines in pencil beyond the limits of the figure ; this is done with fine lines so that the extra portions may be readily erased. Lay off from the top central point on each side lines making with the top line the following angles: 3^; 11 15'; 23 45'; 36; 50 15'; 62 75'. In laying off these angles, do not go around the drawing- board ; remain in the usual place. Ink-work. Draw all the first lines full lines as fine as the pen^will sustain ; draw the lines laid off with the help of the protractors in fine broken lines. The center line is a black-ink line like the others to the boundaries and is extended in red ink half an inch above and below. The arcs for measuring angles are drawn in red ink and spaces are left for figures except where the drawing is too crowded ; in this case draw an arrow to a convenient point outside the figure and place the reading of the angle there. Place the figures for the angles vertical. This is done because, if they were placed according to rule at right angles to the dimension lines they could not be read from the proper angle of the board. 1 3 2 ME CHA NIC A L D KA WING. Place the average readings of the corresponding angles on one side only of the vertical center line. According to sizes place alternate readings of angles on each side of the vertical center line. Legend. The legend reads: SHEET I. STRAIGHT-LINE DRAWING. Name [F. K. Jones.] Class [Fourth Class.] Date [Dec. I, 1900.] The space to be used is divided and the sizes of the lettering arranged by each one according to his judgment. " Sheet I " and " Straight-line Drawing " are made in block letters of two different types, but of straight lines only. The remainder of the legend except the name is made in "free- hand lettering. ' ' The name is an autograph. Above each figure the number of the figure is centrally placed, as Fig. I, Fig. 2, etc., in "free-hand lettering." The bottom line of the lettering is y&" above the top of the figures. The scale is centrally placed below each figure, the bottom line of the lettering S/Q" below the bottom of the figure. This is also "free-hand lettering." The effect is improved by drawing moderately heavy black lines just under the lettering. Border Line. After the lettering is completed, the border line is drawn. See " Border Line." The drawing is cleaned and finally inspected. It is then cut from the board and paper is stretched for the next drawing. SHEET II. CIRCLES: TANGENTS: ARCS MEETING ARCS: IRREGULAR CURVES: SHADING ARCS: FILLETS. LAY out the Sheet and follow the directions for Sheet I. Do not sketch the general plan of the Sheet, as it is the same as Sheet I. SHEET II. FIG. 1. Scale, full size. Compass. T square ; triangles ; compasses ; same radius for all circles ; full lines in pencil and ink ; varying widths of lines in ink-work. See remarks under "Compasses." 133 134 MECHANICAL DRAWING. Pencil-work. Center the figure by drawing diagonals. Use the center of figure as a center and a radius to the middle point of one side and draw a circle. Take care to properly bend the knees of the compass. This circle should exactly touch the boundaries at the middle points. Begin at the middle point of the left-hand boundary line and with the same radius as before draw an arc ending at the boundaries of the figure. Use the point where this arc cuts the first circle drawn as a center and draw another arc ; and so on around until the last arc drawn passes through the first center used on the left. Every one of these arcs should pass exactly through the center of figure. From each of the corners of the figure and from the remain- ing middle point of the side as centers draw arcs. Those drawn with the corners as centers should pass exactly through the middle points of the sides and those drawn with the middle points of the sides as centers should pass exactly through the center of figure and the corners. Ink-work. Set the pen for the first circle and first set of arcs drawn. Make this a fair line not as fine as the pen will make and draw a sample line on the margin of the paper where others may be compared w r ith it at will. Draw the first circle. Draw the arcs until they end at the first circle. Set the pen for the other arcs, making the sample line four times as heavy as the first sample line. Draw the arcs that have the corners as centers, extending them to the boundaries. Draw the arcs that have the middle points of the sides as centers only where they extend beyond the first circle drawn. As some of these arcs begin to be heavy at the original circle and are light inside of it, care must be taken to begin the heavy part exactly at the circle. Note also that some of these arcs do not extend within the circle at all. Arrange the extra width of the lines so that it does not pass beyond the boun- daries. Go over the first circle again with the wider line ; arrange FIRST DRAWINGS. 135 the extra width so that it does not pass beyond the boundaries of the figure. Draw the diagonals and the center lines in red ink. SHEET II. FIG. 2. Scale, 4" = i foot. Compasses, bow pencil, and pen. T square ; triangles ; triangular scale ; compasses ; bow pencil and pen; full lines, pencil and ink, varying widths in ink. Pencil-work. Center the figure. Draw the center lines. From the middle point of the top boundary line measure down- ward the following dimensions: yi" \ Y%" ', ^Y%" ', i^'; 2^T' '; 3^"; 4^3 " . The remaining distance to the center is y^" . Using the bow pencil (see notes under "Bow Pencil") with the center of figure as a center draw circles through each of the points marked. From one corner of the figure measure along the diagonal the following dimensions: 1 1>"; 11^6"; n^i"; 12^". Using the compasses with the center of figure as a center, draw arcs through the points marked, extending them to meet the boundaries. 136 MECHANICAL DRAWING. Ink-work. Using the bow pen (see notes under "Bow Pen"), draw the smaller circles. Make the outer one that tangent to the boundaries a heavy line and the others gradually decreasing in width to the inner one, which should be as narrow a line as the pen will make. Place the extra width of line on either side of the pencil-line. Using the compasses, draw the outer arcs, decreasing the widths of the arcs as each arc becomes more distant from the line tangent to the boundaries, and in the same manner as for the inner lines. Draw the diagonal used and the horizontal and vertical center lines in full lines with red ink. SHEET II. FIG. 3. Scale, full size. Bow pencil and pen. T square ; triangles ; triangular scale ; bow pencil and pen ; full lines in pencil, full and broken lines in ink. Pencil-work. Draw the center lines. Divide each of these lines into six parts by any method and draw vertical and hori- zontal lines through these divisions. Draw arcs as shown, using a radius equal to the length of the diagonal of two adjacent squares. Take time in getting the exact radius by FIXST DRA WINGS. 137 trial at several points and do not change this radius while drawing the arcs. Ink-work. Set the pen as exactly to the correct radius as possible and do not change the setting while drawing the lines. Make the lines quite fine. Draw every other pair of arcs full lines and the remaining ones broken lines with dashes about After all the arcs are drawn, go over the top and bottom rows of full lines, making them about four times as heavy as before, keeping the extra width of line within the boundary lines. Draw the vertical and horizontal lines in red ink. SHEET II. FIG. 4. Scale, full size. Bow pencil, bow pen, bow spacers. T square ; triangles ; bow spacers ; bow pencil and pen ; full lines in pencil and ink, heavy lines in ink. Pencil-work. Divide the top and one of the vertical sides into six parts by drawing lines at an angle and spacing off dis- tances, using different lengths of space for the two lines. Draw vertical and horizontal lines through these divisions ; draw diagonal lines for the figure and lines parallel to them 138 MECHANICAL DRAWING. from the points marked off. Use the intersections of these last lines as centers and draw circles tangent to the vertical and horizontal lines. By trial of a few spaces decide on the radius that will bring the closest approximation to the correct one for all the spaces and use that radius for all. Ink-work. Draw all the circles in fine lines and make the alternate ones, as indicated, heavy circles. These lines of the circles are - s " wide, and the thickness is on the inner side of the line first drawn. Draw the outer and inner circles quite heavy and fill in by changing the set of the bow pen and open- ing the points wide. Draw the auxiliary lines used for dividing the sides into equal parts and the lines for marking the centers of the circles full lines in red ink. The vertical and horizontal lines are drawn in black ink and are fine lines. SHEET II. FIG. 5. Scale, 2" = i foot. Fillets. T square ; triangles ; triangular scale ; bow pencil and pen ; full lines in pencil, full and broken lines in ink. Pencil-work. Draw the center lines. On the horizontal FIRST DRAWINGS. 139 center line measure from the center to right and left the fol- lowing dimensions: i^"; 2^"; 4^"; 6"; 7^"; 8^"; 9". On the vertical center line measure from the center upwards and downwards the following dimensions: 2%" '; 4"; 5^"; 6?<"; 7 3 /T; 8^"; 9"- Construct rectangles with the use of the T square and tri- angles on the corresponding measurements. Connect the corners of the rectangles with small arcs or " fillets," as fol- lows : For the N. E. corners, use radii in succession, beginning with the inner rectangle, as follows: ^"; i" ; i%"\ 2"; 2^"; i " ' 1 1/ '' 3 > 3/2 For the N. W. corners, as before, use the following radii: %"; iX"; iti"; 2^"; 2i/ 4 "; 3 ^" ; 3 y 4 ". For the S. W. corners, as before, use the following radii: T " !!/" ^>" 1\/ n ' l" ' *>\/"- A" 1,1/2,2, 2/2 , 3 , 3/2 , 4 . For the S. E. corners, as before, use the following radii: i#"; itf"; 2^"; 2^"; 3^"; 33^"; 4 ^". In drawing these fillets, from the corner of the rectangle swing an arc around of the correct length to cut the adjacent sides of the rectangle. From these points swing arcs of the same radius to meet each other. These last points are the centers from which to draw the fillets. Many draftsmen of experience do not take the trouble to define these centers, but find them rapidly and accurately by trial. Carefully draw all these fillets with the bow pencil. Mark the centers clearly. Swing the arcs beyond the points of tan- gency, as it is impossible to determine that the arc is exactly right if it stops on the line. Ink-work. Ink all the fillets first with comparatively fine lines. The upper half of the figure is drawn in full and the lower half in broken lines with dashes varying according to the size of the rectangles. In inking the straight lines, carefully set the bow pen for 140 MECHANICAL DRAWING. the first line to agree with the line of the fillets. Draw the vertical lines first one after the other, beginning at the left. Always draw from the fillet at the left hand towards the one at the right and stop the line near the fillet and draw a line from the right-hand fillet to meet the previously drawn line. This allows of a slight moving of the pen from or towards the triangle or T square to meet the other line fairly. This case of drawing a straight line to meet two curves is the only one where it is advisable to break the general rule of drawing from left to right. Draw the center lines in red ink, and show in red ink in one corner of one rectangle only the method of finding the center of the fillet. SHEET II. FIG. 6. Scale, f" = I foot. Arcs and straight lines. T square ; triangles ; triangular scale ; bow pencil and pen ; full lines in pencil, full and broken lines in ink. Pencil-work. Draw the diagonals. From one of the lower corners of the figure measure along the diagonal the following distances, each measured from the corner: 2" ' 7"; 16"; 2 ft. 3", 3 ft. 5"; 4 ft. 10". FIRST DRAWINGS. 14! Begin with the corner as a center and draw an arc, using the first dimension as a radius ; using this first point measured as a center and the distance from that point to the second one as a radius, draw another arc ; repeat this operation for all the points measured on the diagonal. These arcs are drawn as complete circles, though all of the circumferences are not drawn in ink. From the same corner measure along each of the sides adjacent the following dimensions, each measured from the corner: 2^"; 10"; 15"; 23"; 2ft. n"; 4ft. From the adjacent corners measure towards the first corner these same last dimensions. From each of the measurements taken from the first corner along the sides of the figure in succession draw tangents to the arcs drawn in succession, the first tangent being drawn from the first measurement to the first arc, etc. From each of the measurements made from the other two corners in succession draw tangents to the arcs in succession, the first tangents being drawn from the first measurements to the last arcs drawn, etc. NOTE. Always draw the tangent away from the arc, not towards it. These tangents are drawn by trial, using a triangle. There is no attempt made to find the point of tangency. From the center of figure towards the corner of the figure diagonally opposite the first corner used, measure along the diagonal towards that corner the following dimensions, each measured from the center of figure: 3"; 8"; 14"; 21" '; 2 ft. 5"; 3 ft. 2"; 4 ft. i". Begin with the center of figure as a center and draw an arc, using the first dimension as a radius; using the first point measured as a center and the distance from that point to the second one measured as a radius, draw another arc ; repeat this operation for all the points measured on the diagonal. Using the last point measured as a center and such a radius as will 142 MECHANICAL DRAWING. make the arc tangent to the two adjacent boundary lines of the figure, draw an arc. These arcs are drawn as complete circles, though all of the circumferences are not inked. From the center of figure measure along each 'part of the diagonal which is at right angles to the one along which these last measurements were made, the following dimensions: 3" '; 5"; 10"; 21"; 2 ft. 9"; 3 ft. 10"; 5 ft. l". From each of these last measurements in succession draw tangents to each of the arcs last drawn in succession, the first tangents being drawn from the first measurements to the first arc, etc. These tangents are on the same side of the diagonal as the point. From each of these last measurements in succession draw tangents to each of the arcs last drawn in succession, the first tangents being drawn from the first measurements to the last arc, etc., the final tangents to the smallest arc being drawn from the corners of the figure. Tangents as above. These tangents are drawn as before, by the use of the tri- angles only, with no attempt at finding the points of tangency. Ink-work. Use a fine pen. Draw the first set of arcs in full lines, extending them only to the points where the tangents meet them. From these arcs draw the first set of tangents in full lines to the boundaries. Draw the second set of tangents from these arcs in broken lines with dashes about ^" long, extending them to the boundaries. Draw the second set of arcs in broken lines, the lengths of the dashes as before, and extend them as before only. From these arcs draw the first set of tangents in full lines to the diagonal only. From these arcs draw the second set of tangents in broken lines, extending them to the diagonals. Draw the diagonals in red ink. FIRST DRA WINGS. 143 SHEET II. FIG. 7. Scale, " = I foot. Two arcs and straight line joining them. T square ; triangles ; triangular scale ; bow pencil and pen ; connecting tangents with arcs; full lines in pencil, full and broken lines in ink. Pencil-work. Draw the center lines. With centers on the horizontal center line, draw arcs tangent to the side boundary lines at the middle points with the follow- ing radii : 2 ft. 6^"; 2 ft. 3"; I ft. 9^"; i ft. 2^"; 8"; 2". Connect these corresponding arcs above and below the horizontal center line with straight lines, using the triangles only. Draw a line away from the left-hand arc and extend it to near the other arc ; then break the established rule of draw- ing lines from left to right and draw a line away from the right-hand arc to connect with the line already drawn. The T square moved up and down the board is a check on the work. With centers on the vertical center line draw arcs tangent 144 MECHANICAL DRA WING. to the top boundary line at the middle point with the following- radii: 2 ft. 8"; 2 ft. 4"; I ft. 10^"; i ft. 3"; 8^ /x ; 3". Connect these arcs with tangents to the nearest bottom corner of the figure on the same side of the vertical center line. With centers on the vertical center line draw arcs tangent to the bottom boundary line at the middle point with the fol- lowing radii: 2 ft. 9"; 2 ft. 5"; I ft. ny" \ i ft. 4" ; 9^"; 3#" Connect these arcs with tangents to the farthest top corners of the figure on the further side of the vertical center line. The T square carried down the board is a check on the accuracy of the work, as the points of tangency on the sides of the vertical center line for any arc should be on a horizontal line. Carefully draw tangents from arcs. Ink-work. Draw the first set of arcs and tangents in full lines, making the inner one a fine line and increasing the width of the other lines as the radii increase. Draw the set of arcs that are tangent to the top line and their connecting tangents as fine broken lines with dashes about y" long. Draw the set of lines that are tangent to the bottom line and their connecting tangents as broken lines twice as heavy as those previously drawn, but with the same length of dashes. Draw the vertical and horizontal center lines in red ink. FIKST DRAWINGS SHEET II. FIG. 8. Scale, full size. Protractor, arcs, and straight lines. T square ; triangles ; triangular scale ; protractor ; full lines in pencil, full and broken lines in ink. Pencil-work. From the two bottom corners lay off upward from the bottom line and within the figure the following angles : 5; 11; i8 3 o'; 27; 36 30'; 48; 60 30'; 74; 88 30 . Join seven of the corresponding pairs of lines with tangen- tial arcs of the following radii in succession, beginning \vith the lines drawn from the smallest angles: 2", i^"; i/^"; i^' '; i"; Y^' 1 '; YZ" . For the next set of lines use a radius that will make the arc tangent to the two lines and to the top boundary line. For the last set of lines, use a radius of ^" and draw arcs tangent to the lines and to the top boundary line. The centers are found by trial. From the two top corners lay off downward from the top line and within the figure the following angles: 6 30'; 12; 19; 28 30'; 37; 49 30'; 61; 75; 89. Join seven of the corresponding pairs of lines with tangen- 146 MECHANICAL DRAWING. tial arcs of the following radii: i^"; i%"\ i^"; i"; Y \ YZ" ; %" . Finish the two remaining sets of lines as be- fore. The centers are found by trial. Ink-work. Ink all the arcs first and draw the straight lines away from the arcs. Make the set of lines from the lower corners and corresponding arcs in fine full lines and those from the top corners in equally fine broken lines with dashes about y%" long. Draw the vertical center line in red ink. SHEET II. FIG. ( J. Scale, 10. Tangent arcs. T square ; triangles ; triangular scale ; compasses ; bow pencil and pen; full arcs in pencil, full and broken lines in ink. Pencil-work. Center the figure and draw center lines and diagonals, extending these lines beyond the boundaries of the figure about 3". From the center of figure measure on one of the center lines in one direction only the following dimensions: '.'50; '.'75; i"; i'.'2S; r/75; 2'.'2 5 ; 3"; 4"- FIRST DRAWINGS. 147 With the bow pencils and compasses, swing these dimen- sions around the central point and mark them on the other side of the center line used and on both sides of the center line not first used. With these points as centers draw arcs tangent to the adjacent diagonals, 'extending them just enough beyond the diagonals to ensure their tangency. These radii are determined by trial only. Checks for the work are circles drawn with the center of figure as a center and radii to the points of tangency of corre- sponding arcs on the diagonals. Ink-work. Draw the arcs from diagonal to diagonal only in fine lines. The two sets of arcs on the sides and the one set above the center are full lines; the lower set of arcs is drawn in broken lines with dashes about T y long. Draw the auxiliary and check lines in red ink to the boundaries only. SHEET II. FIG. 10. Scale, |" = I foot. Connecting arcs. 148 MECHANICAL DRAWING. T square; triangles; triangular scale; bow pencil and pen; compasses; connecting arcs with each other; full lines in pencil and ink, full and broken lines in ink. Pencil-work. Center the figure and draw the center lines. With the center of figure as a center and the following radii draw semicircles in the upper part of the figure ending on the horizontal center line : 2" '; 4%"; 7/^ ;/ ; ii /r ; 15"; 19^"; 24". With the extremities of the horizontal center line as centers draw arcs connecting with each end of those previously drawn, extending them to the boundaries of the figure. With the four corners of the figure as centers draw arcs from the points where the last arcs cut the vertical sides of the figure, extending these arcs to the boundaries. Ink-work. Draw the first set of lines and the connecting lines in fine ink lines. Draw the arcs made with the corners of the figure as centers in fine broken lines. Draw the center lines in red ink. SHEET II. FIG. 11. Scale, full size. Connecting arcs. FIXST DRA WINGS. 149 T square ; triangles ; triangular scale ; bow pencil and pen ; compasses; full lines in pencil, full and broken lines in ink. Pencil-work. Center the drawing by diagonals. Find the middle points of the half diagonals running N. E. and S. W. From the lower one of these centers draw arcs with the follow- ing radii:. #"; M"; }"; 5/ 8 -; #". From the upper one of these centers draw arcs of the fol- lowing radii: y 8 "; y" \ S/Q" '; y 2 " '; y%". Connect the arcs on the lower side, beginning with the largest of each set, by arcs with the following radii in succes- sion: 2'' '; 2 T 1 - g - // ; 2^"; 2 T Y'; 2^' r . These arcs are convex looking from the top down. Connect the first set of arcs on the upper side, beginning with the largest of each set, by arcs with the following radii in succession: 3^"; 3 T y'; 3^"; 3 T V'; 3^". These arcs are concave looking from the top down. The centers of these arcs are found as follows : On any line through the center : ">,'"" QF THi SRSITY OF . .&ILIFQBSS! 152 MECHANICAL DRAWING. T square ; triangles ; triangular scale ; bow pencil and pen ; compasses; irregular curves; full lines in pencil and ink. Pencil-work. Center the figure and draw the center lines. From the center measure upwards the following dimen- From the center measure to right or left the following dimensions: %" \ Y 4 " \ i"; i^ /r ; i }&" . The corresponding horizontal and vertical distances are semiaxes of ellipses. Construct the largest three of the ellipses on these axes extended to the other side of the center, by the following method : Draw AB. With O as a center swing the distance OB to the point D. Take the distance AD and measure it from B to C. Bisect A C and extend the bisecting line to meet the vertical axis at E. With E as a center and a radius EB draw an arc to right and left of B, extending it to the line EK. With H as a center draw an arc with HA as a radius ; this line will meet the line of the ellipse drawn from B with E as a center, and this method of construction is an approximate method of constructing an ellipse. If the work is not done with the utmost accuracy, the irregular curves must be used to join the arcs fairly. See note under " Irregular Curves." The remaining portions of the ellipse and all parts of the other two ellipses are constructed by this method. Construct the remaining ellipses by the following method : From M lay off the semiminor axis, ON, to the point R. With the length RP as a radius describe arcs through N and S. Make OT = \OR. With T as a center draw an arc through M. If drawn with care this arc meets those already drawn. Ink-work. Draw the arcs of the ellipses first and finish with the irregular curves later, if necessary. Care is required in carrying the arcs just far enough and not too far. The lines are all full lines. Draw in red ink the construction lines of one-quarter of only one ellipse drawn by each method. Also draxv the center lines in red ink. FIRST DRA WINGS. 153 SHEET II. FIG. 14. Scale, if" = i foot. Irregular curves. T square; triangles; triangular scale; irregular curves; full lines in pencil, full and broken lines in ink. Pencil-work. Divide the horizontal center line into twelve equal parts, using the triangular scale. On the two outside lines next the vertical boundary lines measure off from the horizontal center line, above and below, the following distances: 6" ; 7"', 8"; 9"; 10"; each measured from the center line. On the next two interior lines on each side measure off in the same way the following distances: 8^"; 9"; 10^"; ii"; li#". On the next two lines measure the following distances as. before: &#"; 9%"; 10^"; n#"; 12". On the next two lines measure the following distances as before: 7^''; 9"; 10"; \\" '; ii^ 7/ . On the next two lines measure the following distances- as before: " 8" " ' 10" \\" . 154 MECHANICAL DRAWING. On the middle line measure off as before the following dis- tances: 7"; 8#"; 9^"; 10^"; n^". See notes under " Irregular Curves." Through the ends of the horizontal center lines and the corresponding measurements draw smooth curves with the aid of the irregular curves. Each line is to be tangent to the vertical boundary line at the middle points. Note that the curves correspond on either side of the center lines. Ink-work. Draw the upper lines full lines with a fine pen. Draw the lower lines broken lines with the same width of pen-opening and dashes about y%" long. Draw the vertical lines and the horizontal center line in red ink. \ \ \ SHEET II. FIG. 15. Scale, full size. Shading fillets. T square ; triangles ; triangular scale ; bow pencil and pen ; full lines, pencil and ink. Pencil-work. The figure represents a number of blocks piled centrally on each other. FIRST DRA WINGS. 155 Draw the center lines. On one of these lines measure from the center the following dimensions: T \ /x ; Swing these dimensions around to the other three portions of the center lines. Draw squares, using the corresponding- dimensions. Diagonal lines are cJiccks on the accuracy of the work. Draw fillets at the corners of all the squares with the fol- lowing radii in succession, beginning with the smallest squares: 3//. 1". I/" 9 ". 8"' 11". 3,6" fV > 3 > /4 > "32- > T^ > -3 ' 7 8 ' Ink-work. Draw the fillets first and complete the squares with the rounded corners in full lines with a comparatively fine pen. Shade the blocks according to the notes under " Shade Lines." Draw the center lines and the diagonals in red ink. Show in red ink how one of the centers for the fillets is found. SHEET II. FIG. 16. Scale, i" = i foot. Shade lines. 156 MECHANICAL DRAWING. T square ; triangles ; triangular scale ; bow pencil and pen ; shade lines; full lines in pencil and ink. The figure represents blocks resting centrally on each other, the smallest on top. Pencil-work. With the center of figure as a center draw circles with the following radii: 2"; 3^" ; 5^"; 8"; n"; Ink-work. See notes under "Shade Lines." Draw and shade the four outer circles by the first method. Draw and shade the three inner circles by the second method. Draw center lines and diagonals in red ink. SHEET II. FIG. 17. Scale, i" = i foot. Heavy lines with narrow spaces between. T square ; triangle ; triangular scale ; bow pencil and pen \ compasses ; shade lines ; full lines in pencil and ink. The figure represents sections of sheet metal standing on end. Where the sheets lap, a fine white line is left, the entire width of this being taken from one sheet. The ends of the laps are closed, as shown. FIRST DRAWINGS. '57 Pencil-work. Use the center of figure as the center for the rings of metal. The radii of the mean diameters of the rings are as follows: 3"; 6"; 9"; I2#"; 16^". The thicknesses of the sheets, beginning with the outer ones, are: i#"; I"; i/ 4 " ; #"; tf". Make the joints for the outer rings at the sides and for the next inner one at top and bottom. Alternate to the innermost one. The laps are 30 long, half on each side of the center line. Construct the joints of plating. Ink-work. Carefully draw the boundaries of the metals with quite a fine opening of pen and fill in with a widely opened pen. Do not attempt to bring the heavy ink-lines sharply to the ends. Finish them off with the triangle and R. L. pen. Draw center lines in red ink. SHEET II. FIG. 18. Scale, 2" = i foot. Shading circles: Hatching. T square; triangles; triangular scale; compasses; bow pencil and pen ; shading circles ; full lines in pencil and ink. 158 MECHANICAL DRAWING. The figure represents a section of a hollow shaft showing beyond the section the enlarged portion for the coupling to join it to the next shaft. The coupling rests on the rectangular block and the shaft is vertical. Diameter of the outer circle of the coupling. . . 18" Diameter of the outside of the shaft 10" Diameter of the axial hole in the shaft 6" Diameter of the bolt-circle i^" Diameter of the bolts 2 y" Number of bolts 6 Pencil-work. Draw the center lines. The central point is the center of the shaft. Ink-work. After the figure is completed, shade the circles. Draw the center lines and the bolt-circle in red ink. Dimension the drawing in accordance with the notes under " Dimension Lines." Mark the centers of the bolt-holes with short full radial lines in red ink. These are at right angles to the bolt-circle, thus marking the centers properly. Hatch the section. See "Standard Hatching." Legend. The legend is placed in the space left for it and is the same as that for the first sheet, except as follows: SHEET II. CURVED-LINE DRAWING. The block lettering is of two types. Curved lines are used where possible. After the drawing is cut from the board, paper is stretched for the next drawing. SHEET III. WORKING DRAWINGS. SKETCHING; VIEWS; CENTER LINES; PROJECTION; SECTIONS; HATCH- ING; DIMENSIONS. (SEE REMARKS UNDER THESE HEADS.) Description of Models. Three brass models are used for this sheet. These are cut across in certain planes and the parts are pinned together. They may be separated into parts in order to study and draw sections. The models are consid- ered to be solid and are drawn accordingly. The lines of separation are generally along center lines. The dowel pins and holes are not drawn. The different models of each kind differ slightly in dimen- sions, so that care must be taken to note the marks on the models used, as it may be necessary to again refer to them after the sketches are made. Models are marked on each portion with the same characters. Where the portions are of the same shape, center-punch marks are placed opposite each other on opposite sides of a plane of separation: as, = , : : , :::-, etc. This conforms to engineering practice. GENERAL DIRECTIONS FOR WORK. Stretch paper for this sheet. The drawings of the views are to " Scale, full size." The sheet is to be inked and completed, not traced. Sketch model I. Inspection of sketch. Pencil the views of model I on drawing-paper. 159 1 60 ME CHA NIC A L D J?A WING. Inspection. Cover drawing with paper. Same, model II. Same, model III. Pencil legend. Inspection. Ink and completely finish the views of model I. Inspection. Cover drawing with paper. Same, model II. Same, model III. Ink legend, draw border, clean drawing. Inspection. Cut drawing from board. GENERAL DESCRIPTION OF SKETCHING. Sketches of the different views of each model are first made in the sketch-books. Note carefully that no instruments but the medium hard lead-pencil are used in making the sketches. Even the center lines and the arcs must be drawn free-hand. Only the foot rule and the calipers are used in making the measurements. Unless the model is large, it is best to make the sketches of such a size that they will all go on one page or two facing pages of the sketch-book. The different views must be pro- portioned in size to the real sizes of the views of the models. As the number of views and sections required for this sheet are given, decide for each model whether to make them of a size that will fit on one or two pages and thus decide approxi- mately how large each view must be sketched and the position it will occupy in the sketch-book. Always fix the positions of the Plan, Front Elevation, and Side Elevation first and draw them first. Later on, place the sections where most convenient. If the book is large enough FIRST DRA WINGS. l6l to place the sections so that they may be partly projected from one of the other views, it is well to arrange the positions of the sections accordingly. Generally, however, sections are placed in any convenient position after the main views are drawn. It is generally best to draw the Plan first and project from that for the Front Elevation, but it must be decided upon in each case. First draw the vertical center line for the Plan and Front Elevation. Then decide on the position of and draw horizontal center lines for the Plan and for the Front and Side Elevations, if the views are symmetrical about centers. Next draw a ver- tical center line for the Side Elevation. This establishes the positions of the central points of the views, if symmetrical. If the views are not symmetrical, decide on whatever center lines there are and draw them. After deciding on the view to be sketched first, place the object or yourself in such a position that the face that is to be sketched of the model is normal to the line of sight. Draw the principal boundaries first, if the figure is symmetrical care- fully making the corresponding boundaries equally distant from the center line. Draw all lines that appear to view first and later put in the hidden lines as broken lines. After the first sketch is completed, draw next the one that seems most easily sketched and measured. Each correspond- ing point and line must be projected vertically or horizontally. After the Plan, Front Elevation, and Side Elevation are sketched, place all the necessary dimension extension lines; then the arrows ; then the dimension lines. Measure the model and place the dimensions in the spaces left. Place each dimension once only on the views, but choose a position for it that will show it clearly. Mark where advisable on these views in heavy broken lines the positions of the planes where the sections are to be taken ; mark the ends of these broken lines; A- - - -B, C- - - -D, etc. 1 62 MECHANICAL DRAWING. After the three views are dimensioned, separate the model at the plane where a section is to be made and place the sec- tion normal to the line of sight. Either portion may be drawn as desired, but one is generally more important on account of the part of the model beyond the section plane. Note that part of the figure is removed entirely, and the part remaining only is drawn and the surfaces cut by the plane hatched. Choose a position in the sketch-book, if there be space, so that as many points as possible may be projected from a view already drawn ; if the size of the book and the other sketches do not allow of this, place the section wherever convenient and sketch the portion of the model remaining as if it were a new model, making the sketch as near the size of the corresponding view already drawn as possible. Draw the vertical center line and any other center lines first. As before, draw all lines that appear to the eye first and later the hidden lines. Note that all the lines beyond the section plane must be drawn. When completed, hatch rapidly, free-hand, either a portion or all of each surface cut by the plane, using the proper Standard Hatch- ing. Hatch enough to clearly indicate what metal is used and how far the surfaces extend. Mark the section sketched, Section on , to agree with the letters placed on one of the other views to show where the section is taken. Make sketches of all the required sections. It is seldom, except in very complicated drawings, that many dimensions are placed on a section. It is never done if the dimensions may be conveniently placed on the other views. Over the sketches for this sheet only place the names of the views sketched and draw projection lines for every point or surface projected. The projection lines are short dashes and extend for only a distance of y^" to 3/s" away from the point or surface pro- jected and the same distance back from the position projected to. FIRST DRAWINGS. 163 When all the sketches of each model are completed, they are inspected before the drawing is begun. GENERAL DIRECTIONS FOR DRAWING SHEET III. Working line 15" x 21" Border line 16" X 22" Cutting line 1 8" x 24" The legend is placed in the lower right-hand portion, as usual, and is as follows: SHEET III. [Block lettering of simple type.] WORKING DRAWINGS. [Free-hand lettering, large.] Sketching; Views; Center lines; Projection; Sections; Hatching; Dimensions. [Free-hand lettering, small.] Sketched and drawn from brass models. Scale. [Free-hand lettering, small.] Name. [Autograph.] Date. [Free-hand lettering, small.] Class. [Same.] On this sheet only place the names of the views over them in free-hand lettering. When sections are made, place above the views in free- hand lettering, Section on , using the same letters that mark the section plane in one of the views. This applies to all drawings. On this sheet only draw projection lines for every point pro- jected. The projection lines are not made of dots, but of very short dashes. They extend for only a distance of }" to ^" away from the point projected and the same distance back from the position projected to. They are drawn in red ink. Make the pencil-lines full and broken lines as required. Do no hatching in pencil. Draw no projection lines in pencil. Place no dimensions in pencil. Ink-work. Carry out the established method of drawing all vertical lines first, full and broken, and then sweep down the board with the T square for all horizontal lines wherever found. 164 MECHANICAL DRAWING. When the shade lines are drawn, set the pen to proper width and never change the setting while drawing the shade lines. Carry out the ' ' Plan of Procedure ' ' for inking. Note carefully which lines are to be drawn broken and which surfaces hatched. The sketches should be so complete in these details that they may be followed absolutely in inking the drawing. POSITIONS OF THE VIEWS ON THE SHEET. A distance of y?" separates horizontally all views of the same model. The vertical distances between the views are given for each model. Place the views of model I as follows : Section on CD. Plan. Front Elevation. Side Elevation. Section on AB. Section on EF. The views to the left touch the left hand, top, and bottom working lines. The vertical distances between the views are equal. In the space to the right of * ' Section on CD ' ' is placed : MODEL I. GUIDE-BLOCK. Place the views of model II as follows: Plan Side Elevation, half section on CD. Front Elevation. Section on AB. The vertical center line of the Plan is on the vertical center line of the sheet. The top of the Plan touches the top working edge. A vertical distance of i%" separates the views in the same vertical line. In the space below " Section on AB " and centrally under it is placed : FIRS 7' DRAWINGS. 1 65 MODEL II. BOTTOM JOURNAL BRASS. Place the views of model III as follows: Plan. Front Elevation. Side Elevation, half section on AB. Section on CD. The " Side Elevation, half section " touches the right-hand working line. A vertical distance of y^" separates the views in the same vertical line. In the space to the right of the Plan is placed: MODEL III. CROSS-HEAD. MODEL I. Make a working drawing of the model of a guide-block. Three views, Plan ; Front Elevation ; Side Elevation : and sections through the horizontal center line of the Plan; the vertical center line of the Front Elevation ; and through a hori- zontal plane about y 2 " below the top of the Front Elevation. The figure represents a block of cast iron which is bolted to the framing of an engine by bolts passing through holes (not shown) extending vertically through at the points marked for the centers of the curves of the corners. The rectangular depression acts as a guide to a rectangular rod moving back and forth longitudinally. The moving rod is horizontal, therefore the Plan will be the view looking down on the model placed so that the depressed portion is seen from above. Sketching. Draw the vertical center line for the Plan and Front Elevation; horizontal center line for the Plan; horizon- tal center line for the Front and Side Elevations ; and vertical center line for the Side Elevation. Sketch the Plan. Project downwards from each vertical 1 66 MECHANICAL DRA WING. line of the Plan a series of short dashes. These define the limits of the horizontal lines in the Front Elevation. Sketch the Front Elevation, using these projection lines for limits for the horizontal lines. The lengths of the vertical lines are decided by eye, noting that the boundaries of the view are equally distant from the horizontal center line. Note the , 1- - -> 1 I Tro-nt ;--3 / *L FIRST DRA WINGS. ,6 7 hidden lines showing that the depressions on the vertical side boundaries of the Plan appear as vertical lines in the Front Elevation. These are projected from the Plan, or the surface a projects to a' a". Draw projection lines horizontally from all horizontal lines of the Front Elevation. These define the limits of the vertical lines of the Side Elevation. Sketch the Side Elevation, using the projection lines from the Front Elevation as limits for the vertical lines. The lengths of the horizontal lines are determined by eye, noting that the boundaries of the views are equally distant from the vertical center line, and that the horizontal lengths of this view should agree with the vertical heights of the corresponding lengths in the Plan. Note that the bottom of the depression in the Front Elevation becomes a hidden line in the Side Elevation, the line extending across the view. Dimensions. Place arrows, as shown, for measurements and draw dimension extension and dimension lines. The radii of the arcs in the Plan must be given and the positions of the centers. Note that no dimensions are required for the Side Elevation, dimensions in the vertical direction being given in the Front Elevation and in the horizontal direction in the Plan. The sketches are now complete as far as the main views are concerned. i68 MECHANICAL DRAWING. Sections. Sections are required on planes AB, CD, and EF. Mark these planes on the proper views with heavy broken lines and letter them, as shown. As stated, place these views in the sketch-books to best advantage. Section on AB. Divide the model on the line AB and sketch one portion, looking towards the surface cut by the plane. The position with reference to the model is the same as when the Front Elevation was sketched. Sketch the model as it appears. Note that the outer boundary is the same as that of the Front Elevation. Part of the view could, then, be readily projected from the Front Elevation. Hatch the surface cut by the plane. Use the Standard Hatching for cast iron. Mark the sketch, " Section on AB." Section on CD. Join the portions of the model and divide it on the plane CD. Sketch the larger portion, looking towards the surface cut by the plane. The position with refer- ence to the model is the same as when the Plan was drawn. Sketch the model as it appears. It is exactly the Plan repeated, except that the side portions are hatched where cut by the plane. Part of the sketch could be readily projected if placed at the top or side of the Plan. FIRST DRA WINGS. i6 9 I I ! Section on EF. Join the portions of the model and divide again on the plane EF. Sketch one portion, looking towards the surface cut by the plane. The position is the same as when the Side Elevation was drawn. Sketch the model as it appears and hatch the surface cut by the plane. I/O MECHANICAL DRAWING. Note that the lines showing the intersections of the curved corners with the side boundaries in the middle of the height become vertical broken lines. Part of the sketch could be projected from the Side Eleva- tion and the rest from the Front Elevation. Mark the sketch, " Section on EF." Below the sketches and in the lower right-hand corner of the page, write: Model I. Guide-block. DIRECTIONS FOR DRAWING MODEL I. Pencil-work. After centering the paper and drawing the three dimension lines of the sheet, note that the views to the left of model I touch the left-hand and the top and bottom working lines. From the sketches, decide on the position of the vertical center line of the left-hand views and draw it vertically the whole length of the working line. From the sketches, decide on the total vertical distance remaining for spaces between the views and divide this distance equally for the spaces. Draw the extreme horizontal bounding lines of the views and their horizontal center lines. Check to see that there is the same distance between the views. Plan. Draw the Plan first. Measure when possible from the center lines half the dimensions on either side. Make as few measurements as possible. Measure once and project up and down or sideways for corresponding points. Fix the center of one of the bolt-holes and project in directions at right angles. Fix the center of the diagonally opposite one and again project in directions at right angles. This establishes the four centers. Front Elevation. Project vertically downward from the Plan the lines of the vertical surfaces and draw them across the view of the Front Elevation. Only one measurement -is made F2KST DRAWINGS. I /I that for the depth of the depression in the model. Draw the hidden lines, projecting properly. Carefully mark on the Plan and Front Elevation the posi- tions of the planes where sections are to be taken. Side Elevation. Project horizontally from the Front Eleva- tion, noting that the bottom of the depression in the model becomes a broken line. The horizontal distances need not be measured ; they may be taken with the dividers from the ver- tical distances on the Plan. Section on AB. Project downward from the Front Eleva- tion. The vertical dimensions may be taken from the Front Elevation by dividers. Section on CD. Project upwards from the Plan and make the view the same as the Plan, as in the sketch. Section on EF. Project horizontally from "Section on AB " and downwards from the Side Elevation. The view is entirely finished from these projections. Note the part to be hatched. Ink according to directions. MODEL II. Make a working drawing of a model of a Bottom Journal Brass. Metal: composition. Three views : Plan ; Front Eleva- tion ; Side Elevation, half in section; and a section through the horizontal center line of the Plan. Scale, full size. The model represents the lower half of a pair of " Brasses " in which a shaft revolves. It is made "flat sided" on the under side to prevent its turning in the framing in which it rests. As it is the lower "brass," the Plan is the view looking into the concave surface. In this case, in order to fit better on the drawing-paper, the Side Elevation is taken to the left. Sketching. It will be found best to sketch the Front Elevation first, as one measurement only is required for the 1/2 MECHANICAL DRAWING. diameters of the half circles shown on the Front Elevation, and the radii used will define both ends of the diameters, which may be projected vertically to the Plan. The basis of work in this view is, then, the top line of the brass. Note also that the shape of the ' * flat-sided ' ' portion of the bottom of the '< brass " is drawn in the Front Elevation and the edges projected to the Plan. There are many more hidden lines than in the views of model I ; all must be carefully drawn. Draw the vertical center line for the Plan and Front Eleva- tion. Leave space above for the Plan and sketch the Front Elevation. Project upwards and sketch the Plan. Carefully mark the positions of the planes where sections are to be taken. The Side Elevation is projected to the right or left of the Front Elevation. Draw a vertical center line for this view at the proper distance away from the Front Elevation. Sketch half of this view only the portion to the right or left of the vertical center line. C2J. \ "V To finish the Side Elevation, half in section, separate the model on the plane CD and hold the half that is used in the FIRST DRAWINGS. 173 same position as when sketching the Side Elevation. Sketch half of the half model, placing proper Standard Hatching on the surface cut by the plane. Note that the outline is the same as for the rest of the view, the difference being in the lines seen and hidden, The vertical line separating the elevation from the section 4P .'-ft 1 1 " 1 ~~ ) 1 ^ . - 1 tl EL 1 I -3 174 ME CHA NIC A L DRA WING. is a full line. The center line continues beyond above and below. Mark the view, Side Elevation. " Half section on CD." Dimensions. Place arrows, lines, etc., for measurements, as shown. Note that all the measurements are on the Plan and Front Elevation. All arcs are dimensioned by diameters where possible. Section on AB. Unite the parts of the model and "separate again on the plane AB. Place the half model so that the sur- face cut by the plane is at right angles to the line of sight and sketch it. . Note that the model is now in the same position as when the Front Elevation was drawn, and that the boundary is the same. Hence this view might be largely projected from the Front Elevation. Hatch the surface cut by the plane. Note carefully the hidden lines. This sketch is placed so it may be projected, if possible. Mark the sketch, "Section on AB." Mark the sketches, " Model II. Bottom Journal Brass. " FIRST DRAWINGS. 1/5 DIRECTIONS FOR DRAWING MODEL II. Draw the vertical center line for the Plan, Front Elevation, and Section on AB, and the horizontal center line for the Plan. Draw the horizontal boundary lines for the Plan and the top line of the Front Elevation. On this last line measure from the vertical center line, the radii of the arcs having this point for a center, and draw the arcs ; the distances for the vertical parts of the ' ' flat-sided ' ' portions of the base and draw vertical lines; and the half extreme horizontal dimensions of the " brass " and draw vertical lines. Measure from the top line down the vertical center line for the position of the center of the lower bounding arc and with the proper radius draw the arc. This arc should join tangentially the vertical lines for the outer vertical boundaries. Measure downward from the same point for the position of the bottom of the ' ' flat-sided ' ' portion of the base of the " brass " and for the depth of the vertical flat portion on the two sides. Draw an indefinite line for the bottom flat and measure along it the half widths. This defines the bottom edges. Project across from the measurements taken for the ends of the vertical ' ' flat-sided ' ' portions. Con- nect the two sets of points last found on the two sides. The lines connecting the portions of the under part are thus deter- mined. Project upwards for the Plan. All the necessary measure- ments are made on the vertical center line, and the horizontal lines are drawn in the proper places from these measurements. In this case, all the lines cross the figure to their respective boundaries, which are projected upwards from the Front Eleva- tion. The radii of the curves at the corners are not important, but the approximate radii found for the sketches are used. The radii are about yi" . Draw the vertical center line for the Side Elevation, half in section. Project to the left from the Front Elevation for the horizon- MECHANICAL DRAWING. tal lines. The horizontal dimensions are obtained from the vertical heights of the Plan. Measure always from the vertical center line. Note that the lines are the same for both parts of the view in the pencil-work, some full, some broken. Section on AB. As this is simply a copy of the Front Elevation with a variation in the lines made full or broken, project down from the Front Elevation and take the vertical measurements from it with the dividers. Lay these measure- ments off on the vertical center line as usual and project across. Ink according to directions. MODEL III. Make a working drawing of a model of a cast-steel Cross- head for a small horizontal engine. Three views : Plan ; Front Elevation; Side Elevation, half in section; and a section through the horizontal center line of the Plan. Scale, full size. The figure represents the sliding-block of metal that con- nects the reciprocating or " back-and-forth " motion of the piston and piston-rod in the cylinder with the rotary motion of the crank and the shaft. As the engine is horizontal, the broad, flat portion is below and furnishes a large surface for support as the Cross-head moves back and forth on the guide. Therefore, the Plan view is the one where the flat portion is downwards. The two cylindrical portions show where the forked " con- necting-rod," that connects the cross-head and the crank-pin, grasps the cross-head. These are called journals. The piston-rod is secured through the middle of the square-faced portion between the cylindrical pins. The hole for this is not shown. The projection on the side of the cross-head is for the purpose of securing there a horizontal pump-rod which moves with the cross-head. The center of the hole for the rod is in- dicated. Sketching. In this case the figure is generally symmetrical in the Plan view, but not so much so in the other views ; so the FIRST DRA WINGS. 177 \ -- front 1 78 MECHANICAL DRAWING. vertical center line for the Plan and Front Elevation is drawn and the horizontal center line for the Plan, but no horizontal center line for the Front Elevation and Side Elevation. The vertical center line for the Side Elevation may now be drawn, but it is better to wait until the Front Elevation is completed. Also, it may be readily seen that it is better to sketch the Front Elevation first, as it gives a better view and a better under- standing of the model. Leave room for the Plan above. Draw a center line for the two cylindrical portions, or journals, and extend this for the Side Elevation. Sketch the Front Elevation and project for the Side Elevation and Plan. Mark the views properly. Note carefully what lines of the Plan are concealed by the projecting portions above. For the half-section on AB separate the model on that plane and place it normal to the line of sight and sketch it. The outline corresponds with that of the Side Elevation, as the part remaining beyond the section is a fac-simile of the part already sketched. Note that the circle seen by looking at the end of the journal becomes a broken line in the section, as the nearer cylinder is removed and the farther one is hidden. Note also that the lines defining the outline of the portion for securing the pump-rod are now gone, as all this portion is removed. Mark the sketch, " Side Elevation, half-section on AB. " Dimensions. Place arrows, etc., as shown. The dimen- sions are again placed on the Plan and Front Elevation only. The approximate shapes of the arcs defining the outlines are determined after the drawing is made on the drawing-board, as they are simply clean arcs joining the determined points. The positions of the beginning and ending of these arcs must be accurately determined and noted on the sketches. The center of the pump-rod is the center of the arc around the metal at that place and is accurately shown, as well as the radius of the curve. FIRST DRA WINGS. 179 Section on CD. Separate the model on the plane. Place the sketch as advisable in the sketch-book, noting that portions of it may be projected from any of the other views. It is seen that the outline exactly corresponds with that of the Front Elevation and that the entire surface is hatched. Care- fully draw all broken lines representing hidden lines beyond the section. Mark the sketch, " Section on CD." Mark the set of sketches, MODEL III. CROSS-HEAD. DIRECTIONS FOR DRAWING MODEL III. Lay off along the top working line from the upper right- hand corner the distance of the half width of the Side Elevation and draw a vertical center line of indefinite length for the center line of the Side Elevation. From the sketches, determine the distance between this ISO MECHANICAL DRA WING. center line and the one through the Plan, Front Elevation, and Section on CD, allowing the proper distance between the views, and draw the new center line. Lay off downward on this center line from the top working line the half height of the Plan view and draw the horizontal center line for the Plan. Draw the boundaries of the base in the Plan. From the lower boundary of the Plan lay off the proper amount for the vertical distance between the views and draw the top line of the Front Elevation. Next draw the center line for the journals and continue to draw the figure from the dimensions of the sketches, measuring always along center lines when possible. After completing the Front Elevation, project for the hori- zontal lines of the Side Elevation and the vertical lines of the Plan. Either Plan or Side Elevation maybe finished first; but it is easier to draw the Side Elevation using the dimensions given on the Plan sketch, and then take these dimensions with the dividers from the Side Elevation and use them in drawing the Plan. The curved lines for the boundaries of the curved surfaces extending from the upper to the lower parts of the Front and Side Elevations are not necessarily arcs of circles, but are generally drawn as such, as the pattern-maker does not require accurate curves and will fashion them as required when he makes the pattern for casting. The arcs are drawn tangent at points a (see sketch) and of radii such that the lower portions of the arcs reach the points b. These radii and the positions of the centers on the horizontal line through aa are found by trial. In the Plan, the corresponding curves are approximated to in the same manner. These may be drawn with irregular curves as guides. The curve in the Front Elevation defining the boundary of the surface extending down to the side extension for the pump- rod is drawn as an arc of a circle with its center on the line aa and a radius and position of center (found by trial) to cause the FIRST DRAWINGS. l8l arc to join at a tangent the arc drawn from the center of the hole for the pump-rod. Half-section on AB. This corresponds with portions of the Side Elevation, as shown in the sketch, and is drawn at the same time as the Side Elevation. Section on CD. This is a reproduction of the outlines of the Front Elevation, so that vertical projections define all hori- zontal lengths and the vertical distances are taken from the Front Elevation with the dividers. Carefully draw the horizontal center line first. Ink according to directions. Legend. In inking the legend, use as little time as possible. Do not make the block letters solid unless they are sufficiently narrow so that a stroke of the R. L. pen will suffice. Make the border simple and make the right-hand and bottom lines heavier than the others. The widths of the parts of the border line should be in accord with the rest of the drawing. When cleaned and inspected, cut the drawing from the board. 182 MECHANICAL DRAWING. STANDARD DIMENSIONS OF BOLTS AND NUTS FOR THE UNITED STATES NAVY. Diameter. Area. Threads. Long Diameter. Short D. Depth. Col. i. 'Column 2. Column 3. Column 4. Column 5. Column 6. Column 7. Column 8. Col. 9 . Nut. Nom. Eff. Eff. No. Hex. Sq. w. Head. i .185 .026 2O A it i 1 j A A .240 .294 345 .045 .067 093 18 16 14 -H U If fi- If If 8 r ^ .400 125 13 i ll |. 7 .| T 9 3 454 . 162 12 ji If ti T 9 B" f 507 .202 i II I A l o f | .620 3O2 IO T 7 If *i f J 731 .419 9 21 2 ^V i T 7 g- II 1 I 837 550 8 IF 2^ 5 g- if it I II .940 .694 7 2 3\ 2 T 9 ^ if r l II .065 .891 7 2 T 5 S 2|| 2 i Ii If .160 1.057 6 2 fl 3A 2 jV i^ If .284 1.294 6 2f 3H 2f 9 *T$ u If 389 I.5I5 51 2 M 3f J A If If .491 1.746 5 3A 3l 2| if .616 2.051 5 3*f 43V 2 lf !^f ll 2 1.712 2.302 41 3M 4ff 3i I T 9 5 2 2l 1.962 3.023 41 if 21 31 2.176 3.719 4 4if 5lf 3| III" 2f 2.426 4.622 4 4|f 6 41 2 I 2 f 3 2.676 5.624 4 ii 4f 2 T 5 g- 3 3i 2.926 6.724 4 sit 7yV 5 2 i 31 3* 3.176 7.922 4 7| 51 2 li 3i 31 3-426 9.219 4 6f s| 5f 2| 3f 4 3.676 I0.6I3 4 ?T6 8f o- gJL 4 4i 3-926 12.106 4 7* 9i\ 6| 31 41 4* 4.176 13.697 4 7H io lf 6| 3A 4^ 4l 4.426 15.386 4 Sf 7i 3f 4f 5 4.676 17.173 4 811 i * 7f 3lf 5 5i 4.926 19.058 4 9i 11 1 5 " 8 4 51 5* 5-176 2I.O42 4 9H i iff 8f 4 T 3 F 51 5.426 23.123 4 10^%- I2f 8| 41 si 6 5.676 25.303 4 ioi| 9l 6 STANDARD HATCHING. CAST IRON. WRO'T IRON. CAST STEEL. BRASS OR COMPOSITION. VULCANITE. COPPER. GLASS. BRICK. WOOD. STONE. EARTH. CEMENT. ALUMINUM. 133 SPECIAL METHODS OF THE BUREAU OF ORD- NANCE, NAVY DEPARTMENT. All lines are in black ink. Center lines : One long and two short dashes, slightly heavier than dimension lines. Section planes: Same as center lines. Dimension lines : One long and one short dash. Imaginary positions indicated by : Long dashes. Hidden lines: Short dashes. Dimensions are in decimals for special ordnance work. Special scales are generally used, but the one decimal scale on the triangular scale may answer if calculations are made at the same time. 184 SPECIAL METHODS OF THE BUREAU OF CON- STRUCTION, NAVY DEPARTMENT. All lines are in black ink. Center lines and dimension lines: One long and one short dash. 185 INDEX. Arrows, 60 Beam-compasses, 29 Block letters, 78 to 82 Blue-printing, 98 Bolts and nuts, 70 Bolts and nuts, standard, 182 Border line, 75 Bow spacers, 22, 124, 137 Bow t>encil, 22, 135. 136, 137 Bow pen, 22, 135, 136, 137 Breaks, 56 Brushes, 29 Bureau of Construction, 185 Bureau of Ordnance, 184 Calipers, 30 Center Lines, i, 41 Centers, horn, 28 Compass, beam, 22, 29 Compasses, 19, 133, 135 Compasses, test, 20 Compasses, use, 20 Cone, line shade, 89 Construction Bureau, 185 Curves, irregular, 25 Cutting line, 75 Cylinder, line shade, 86 Dimension extension lines, 57, 126 Dimension lines, 57, 126 Dimensions, 167, 174, 178 Dimensions, figures, 61, 126 Dimensions, figures, decimal, 61 Dimensions over all, 59 Dividers, 24 Dividers, use, 24 Dividing lines into parts, 125 Drawing-board, I Ellipses, 151 Erasers, 27 Erasers, rubber, 27 Erasers, meta 1 , 27 Erasing shields, 28 Extension-bar, 21, 150 File, 4 Fillets, 47,^138, 154 First drawings, 106 Flat tint, 93 General Arrangement, 34 General Remarks, 105 General View, Sheets I and II, 106 Hatching, 51, 128, 157 Hatching, standard, 183 Horizontal lines, I, 7 Horn centers, 28 Ink, black, China, 5 bottled, 5 red, 5 Irregular curves, 24, 151, 153 Isinglass, 29 Jam-nuts, 74 Leads, 2 Lead, sharpening, 3 Lead-wire, 31 Legend, 76, 132, 15?, 181 Lettering, 76 Lettering, free hand, 83, 84 Letters, block, 28, 79 to 82 Light, 2 Lines, 2, 3, 40 border, 75 center, 41 cutting, 75 dimension, 58 extension, 58 shade, 43, 155, 157 187 iSS INDEX. Lines, shade, bolt-heads, 49 sections, shafts, etc, 49 working, 75 Line shading, 85, 129 cone, 89 cylinder, 86 hollow, 89 sphere, 90 Marking dimensions, 5 Models, 159 Model I, 165 II, 171 III, 176 Nuts, 70 jam, 74 Ordnance Bureau, methods of, 184 Pads, for sharpening leads, 5 Paper-cutters, 31 Paper, stretching, 32 Parallel lines, to draw, 8 Pen, right-line, 13 Pencils and pencilling, 2 Artist, 3 points, 3 sharpening, 3 compasses, 3 Pencil, use of, 5 Pencilling drawings, 103 Plan of procedure in making a drawing, 102 Plan of procedure in inking a draw- ing, 104 Pricker, 5, 29 Profile drawings, 34 Projections, 38 Protractors, 26, 130, 145 Right-line pen, 13 clean, use, etc., 13-18 Rule, foot, 30 Scales, TO to 12, 76, 83 Screw-threads, 62 Secure paper on board, 2 tracing-cloth on board, 2 Sections, 50, 128, 168, 174, 179 Shade lines, 43 to 49, 155, 157 Sheet I, 107 II, 133 HI, 159 Shields, erasing, 28 Sketches, 99, 160, 165, 171, 176 Spacers, bow, 22 Sphere, line shade, 90 Splines, 31 Standard bolts and nuts, 182 hatching, 183 Stippling, 95 Tails, 74 Thumb-tacks, 2 Threads, double, etc., 68 screw, 62 square, 67 Tint, fiat, 93 Tinting, 85 to 92 cone, 96 cylinder, 96 sphere, 97 Tracings, 35, 95 Trams, 29 Triangles, 8 test, 9 45, 114, 115, 119, 120, 121 60, 116, 117, 120 to 122 Triangular scale, 10 use, 13 guard, 13 Truing up, i T square, 6 Vertical lines, I, 7 Views, 36 Weights, 7 Wire, lead, 31 Working drawings, 35, 159 business method, 35 Working-edge, I Working line, 75 THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW AN INITIAL FINE OF 25 CENTS WILL BE ASSESSED FOR FAILURE TO RETURN THIS BOOK ON THE DATE DUE. THE PENALTY WILL INCREASE TO SO CENTS ON THE FOURTH DAY AND TO $1.OO ON THE SEVENTH DAY OVERDUE. LD 21-100m-7, '40 (6936s) UNIVERSITY OF CALIFORNIA LIBRARY