Cad

“ There's big men and little men mixed up together, that's all. None of us know where we are. Your cads in a bank-holiday train and your cads on two thousand pound motor, except for a difference in scale, there's not a pin to choose between them. ”

“ Here you trace one winding and creeping, by soft and subdued steps, through the labyrinth of sweet sounds; then another drops, with delicious trickling falls, from the highest compass to the level of the rest; then one seems at length to extricate itself; then another, in imitative successive cadences; they seem as silver threads that gradually unravel themselves, and then wind round the fine deep-toned bass which has scarcely swerved from its steady dignity during all their modulations, and filling up the magnificent diapason, burst into a swelling final cadence, which has no name upon earth. ”

“ The Use of Drawing Instruments, and Geometrical Problems. Elementary Exercises in Water-color Washes. Military Topography—Map Reading and Map Making. Book of Letters and Lettering. Descriptive Geometry Problems.
The work of the second year begins with freehand military landscape sketching in the field; and is followed by memory drawing for the training of the formal memory, and freehand mechanical and projective drawing. Practical projective geometry, including axonometric projection, is then resumed preparatory of the plan, section, and elevation drawing of a building construction project. ”

“ Undoubtedly, too, many enter on this phase of study without adequate preparation, having little appreciation of the underlying geometric construction, not only in design but in all form.
This, on investigation, can always be found, and either the general mass or sub-divisions identified with some simple geometric shape enclosing the more intimate details. Correct approximation and placing are essential to the accuracy and success of the drawing. Too often through lack of training the tendency is to draw detail right away, without the necessary preliminary of determining the mass shapes. ”

“ And to confess the truth, there are easier tasks than obtaining clean, clear, correct geometrical and perspective diagrams, whether in pencil or in ink. And on examination days, woe be to those who are not “well up” in these absolute essentials of certificated merit. To model drawing succeeds the “figure from the flat,” “ornament from the cast,” and lastly, the “figure from the round.” Let it be remembered that each of these studies must be thoroughly mastered in its outline before the pupil is permitted to attempt its shading. ”

“ In drawing these curves great exactitude is required to properly find their centres; nothing looks worse in a drawing than an unfair or uneven junction between curves and straight lines. To find the location for these centres, set the compasses to the required radius for the curve, and from the point or corner A draw the arcs b and c, from c mark the arc e, and from b the arc d, and where d and e cross is the centre for the curve f. ”

“ We have been observing all our lives; we have made careful observations of many details of form and color, perhaps, and close investigation of structure, but we have not analyzed them into terms of drawing. We have not been looking for the planes of surface, or the relative proportions of parts, or for distance or foreground. Now, however, with the desire to be able to sketch readily, we will observe the object or landscape for that special purpose. One sketch will represent only what has been observed by looking in one direction without turning the head. ”

“ B is a flat rendering whose arrangement of masses suggests the pictorial interest of A without denying the flat surface upon which it is printed.
The Materials of Design
Since design is a matter of arrangement, its materials are the masses, lines, and dots which make up the whole form.
A dot theoretically has no dimensions. And a line (being the path of a dot in motion) theoretically has length but no width. While if a line be moved sideways it produces a mass which has area and shape. ”

“ Draw to scale such parts of the sketch as can be easily measured, and put in the remainder in proportion, and make these sketches at the scale at which you are used to working in the office. They will be of immense advantage in giving you a sense of absolute scale.
"There is such a thing as 'absolute scale,' and scale is not simply proportion. A drawing might be made in good proportion, and the building look well if executed a thousand feet long, and yet lose all its effectiveness if executed but one hundred feet in length, the relative proportions of the parts remaining the same. ”

“ Every dimension which an engineer is likely to require to know should, therefore, be plainly written. Nor is it sufficient to give a dimension once only, as on the plan, for example, and to omit it on the elevation or on the section. It should never be necessary to refer to another drawing to find a dimension. The lettering should be clearly executed, and the direction of the lettering should be the same as that of the figuring, an example of which has been given ”

“ An extensive use of models is, however, unwise. The pupil must learn very early how to visualize a solid from the flat outline picture, just as a builder or a mechanic learns to read his working drawings. ”

“ Orthographic, which represents the subject under consideration in one plane only, and from which dimensions may be scaled off, and which is the normal method of preparing an engineering drawing. (2) Perspective or radial projection is made use of by an architect for displaying the elevations of a building, and gives a truer appreciation of the actual appearance of the building than can be obtained by orthographic projection. (3) Isometric projection enables one to show the length, breadth, and thickness of an object drawn to scale on the one drawing. ”

“ An artisan represents a solid by drawing its projection upon two planes at right angles to each other, and a map maker (cartographer) represents the surface of the earth by projecting it upon a plane. A photograph of the class is merely the projection of the class upon a photographic plate (plane) , and when we draw a figure in solid geometry, we merely project the solid upon the plane of the paper.
There are other projections than those formed by lines that are perpendicular to the plane. The lines may be oblique to the plane, and this is the case with most projections. ”

“ In the second kind of exercise the student is asked to reproduce certain views shown to dimensions given in words or in tabular form. In the third kind of exercise the student is required to make, in addition to certain views shown to given dimensions, others which he can only draw correctly if he thoroughly understands the design before him. In the fourth kind of exercise the student is asked to make the necessary working drawings for some part of a machine which has been previously described and illustrated, the dimensions to be calculated by rules given in the text. ”

“ The student of mathematics must learn to grasp the meaning of a figure drawn in black on white paper, or, more rarely, in white on a blackboard, and the sooner he is able to do this the better for him. The same thing may be said of the constructing of models for any considerable number of figures in solid geometry; enough work of this kind to enable a pupil clearly to visualize the solids is valuable, but thereafter the value is usually more than offset by the time consumed and the weakened power to grasp the meaning of a geometric drawing. ”

“ Things apparently the most trivial are sufficient to render inaccurate or to mar the appearance of the otherwise most carefully and skilfully executed design, and as the value of a drawing depends wholly upon its accuracy and its appearance, it is obvious that such matters of detail, however trivial they may be in themselves, demand careful attention. We have, therefore, deemed it desirable to preface our remarks on Plan and Map Drawing with a brief description of the instruments and materials required, and of the mode of using them which experience has shown to be the best. ”

“ Border and cutting lines, spacing the views, blocking-out, dimensions, letters, final lines. Projection and relation of views. Visible and invisible edges.
Work—
Each pupil solve his problem, freehand carefully on scratch paper first, putting on dimensions. Then carefully to full scale with border and cutting lines but no lettering or dimensions, only sheet number and pupil’s name.
Rapid workers exchange problems and solve as time allows.
[111]
GRADE VIII.
(Mechanical Drawing) Lesson 2. Recitation—
The names and relative positions of the three views most used in mechanical drawing? ”

“ Although a single arch, or even a couple of arches, might be sketched fairly correctly without such aid, a cluster of arches presents a more complicated problem, and we should feel justified in using this method of checking perspective.
Circles, we know, are exceedingly difficult to draw correctly. An artist, of course, should draw circles without resorting to mechanical means, but a beginner, on occasion, may wish to check his drawing of a circle by enclosing it in a square. ”

“ Working by the methods of graphic statics, the engineer’s task is, in theory, one of great simplicity. He begins by drawing in outline the structure which he desires to erect; he calculates the stresses and bending-moments necessitated by the dimensions and load on the structure; he draws a new diagram representing these forces, and he designs and builds his fabric on the lines of this statical diagram. He does, in short, precisely what we have seen nature doing in the case of the bone. ”

“ In a mechanical drawing the light is supposed, for the purposes of line shading or of coloring, to come in from the upper left-hand corner of the drawing paper; hence it falls directly upon the upper and left-hand lines of each piece, which are therefore represented [83] by fine lines, while the right hand and lower edges of the piece being on the shadow side may therefore, with propriety, be represented by broader lines, which are called shadow or shade lines. These lines will often serve to indicate the shape of some part of the piece represented, as will be seen from the following examples. ”

“ Besides photographs, an ingenious auxiliary, as a help in study, would be a little cardboard jointed model of an animal. Say it is one to represent a horse, it can be employed by moving the limbs about in their order as they successively make the steps while the artist selects from a series of photographs a cycle of positions for a movement. In making a jointed cut-out model, however, and fastening the limbs by pivoting pins, it is well to remember that the model can be approximate only. ”

“ Much more, then, the student needs to keep himself rigidly to the guidance of nature; and this he can only do by the constant use of the model.
One Figure or Many.—Whether you have one or more figures, the problem may be kept the same. The canvas must balance in mass and line and in color. When you decide to make a picture with several figures, study the composition first as if they were not figures, but groups of masses and line. Get the whole to balance and compose, then decide your color composition. Simplify rather than make complex. ”

“ Geometrical drawing is the art of representing, to the eye, the problems “worked out” by geometricians, and the importance of a knowledge of geometrical drawing is paramount. The student will find that the figures delineated and explained in the next few pages constantly occur in mechanical drawing. Says Walter Smith, State Director of Art Education in Massachusetts, “I have never known a case where a student did not progress more satisfactorily in his studies after a course of practical geometry.”
The elementary conceptions of geometry are few:
1.—A point. ”

“ If, in a certain diagram, whose geometrical history we know, we want to test whether two Lines, passing through a common point, have, or have not, 'the same direction,' we have simply to take any other point on one of the Lines, and observe whether the other Line does, or does not, pass through it. ”

“ Some of these designs have been noticed in the Inspector's report that he had 'found that the teaching of the calculus was leading to a most interesting evolution of design.'
The beauty of some of the designs is unquestionable; and there can be no second opinion about the value of the method, as training, from the point of view of geometry as well as from that of art. What is not quite so obvious at first sight is its bearing on the training of the unconscious mind for science. ”

“ Firstly, there is the shape of the panel itself. A well-known exercise for the Teacher's Certificate under the Department of Science and Art is to give a drawing of a plant adapted to design in a square and a circle. Now in the abstract one would be inclined to select for a circular fitting different forms from those one might select for a square filling, since I always consider that the shape of the space must influence the character of the filling in line and form. ”

“ It follows, then, that to draw a firm line with ease and rapidity, one must have a positive knowledge of what one desires to express, just the length of the line and its relation to all other lines; that is, one must see things or objects in their right relations. ”

“ The most convenient size of paper to work at for an ordinary-sized model will be made by doubling a sheet of the paper as first procured into four. On the paper becoming perfectly dry, the student must carefully draw each elevation of the building the full height from the ground line to the top of the blocking, being particular that every line both perpendicular and horizontal is perfectly true and square, and marking along faintly the lines for the cornice, strings, &c., &c., that may occur. ”