either as the " front elevation " and " end elevation," or, as in the case of buildings, according to tlie point of the compass which they face, as north, south, east or west, etc., elevations. If the object depicted lias an interior which it is desired to show, such a view is termed a Section, which means a cutting, the view produced being that which the observer would see if the object were cut through on, or by, a piane parallel to that upon which the drawing is made.
As the object here is merely to summarise the character ■ istics of the various kinds of drawing, further details will be deferred until the chapter dealing with the method of making orthographic, projections is reached. Ihe drawings upon page 4 illustrate, by means of a simple solid, the several methods herein described, from which a ready comparison of their effect can be drawn.
Isometric Projection or Projection of Equal Mrasures is a method used to depict three sides of an object in one drawing, thus showing its length, breadth and thickness with a minimum of work and a maximum of clearness; it is a suitable and convincing method for rectangular objects only, as those with inclined surfaces are so distorted in the drawing that no true impression of their shape is conveyed by this method.
Its limitations will be dealt with more fully in Chapter VI. Here it will be sufficient to draw attention to the inclined mitre in the " frog " of the brick depicted in Fig. 6, page 4, wherein the junction between the two slopes is indicated by a vertical line, which common-sense tells us it is not. However, it is impossible to show it in any other way by the rules of isometric projection.
Oblique or Parallel Projection is a still simpler method than the last for showing three sides of an object in one drawing. Simple rectangular solids, or those having regular curved outlines such as mouldings, can be shown in this way easily and graphically (see Fig. 7, page 5). In this method the chief face, or elevation, is drawn as it exists
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