Diagrams

Diagrams are used to show the relationships between several objects or to portray the function of an object. Diagrams are similar to illustrations in that they are often pictorial representations of an object, but they are often more abstract than illustrations. For instance, the elements that make up a diagram may not be drawn to scale with respect to each other; rather than give an accurate picture of the appearance of an object, the goal of a diagram is to help the reader understand how the elements in the diagram are connected.

Figure 14 is an abstract, pictorial diagram visualizing a transfer line setup connecting a holding tank to a tank car.

Figure 15 is a pictorial representation of an experimental design for a coolable nozzle, showing the interrelationships of parts.

To use diagrams effectively, follow these guidelines:

• Keep your diagrams simple. Include only those details that will be relevant to your discussion.

• Label the elements of your diagram clearly.

• Identify each diagram with a figure number and a caption.

Photographs

Photographs can provide an overall view of an object, especially when the object is new or strange, or they may record results that rely on visual inspection, such as X-rays or the effects of destructive testing for failure in materials. To use photographs in a report effectively, you must

• Frame your photograph to include only the elements you need to discuss. Extraneous items will only confuse the reader.

• Use only clearly focused photographs, free of shadows. Poor photography frequently mars otherwise effective report presentations. Remember, photographs are hard to reproduce well in printed reports, so you may want to limit your use of them.

• Provide a way of showing relative size in a photograph (unless your photograph is of something very large-scale, such as a landscape or a whole factory). Show relative size in a photograph by placing some commonplace object of fixed size (such as a ruler, a coin or a pencil) next to the object being photographed.

• Identify each photograph with a figure number and a caption, as you would any other kind of figure in a written report.

If you need photographs for an oral presentation, use a 35-millimeter projector to display them. Photographs transferred to overhead acetates by photocopying machines are usually too dark to be easily viewed by the audience.

Exploded Views

Exploded views present the interrelated parts of a complex object in near proximity so that your audience can see at a glance the total effect of the placement or interaction of part to whole, as shown in Figure 18.

All parts of an object in an exploded view are identified by name. The figure as a whole is given a number and a caption in a written report.

Figures of this type are useful for quick, at-a-glance introduction of complex objects (sometimes, the point of an exploded view is to show just how complex a familiar object can be). Exploded views do not allow you to focus on parts of the apparatus, however. Therefore, combine this kind of illustration with more detailed illustrations for a complete analysis.