1. Assume that you are on the job and that your new supervisor needs detailed knowledge about a mechanism you commonly work with. The mechanism could be a mechanical object, such as a machine or a form, or it could be non mechanical, such as a corporate structure. She will use the description a’s background for a series of meetings she will have with other supervisors. Write a memo of four or five paragraphs. Use the “Skin fold Calipers” memo (pp. 194-195) as a model. Use a visual aid.

2. Assume that you have a new supervisor who needs to understand a process that you use in your job. Describe the process in a memo of four or five paragraphs. Use a visual aid. Use the “Skin fold Calipers” memo (pp. 194-195) as a model for the form.

3. Write an article for a company newsletter, describing a common process . on the job Use a visual aid. Sample topics might include the route of a check through a bank, the billing procedure for accounts receivable, the company grievance procedure the route of a job through a printing plant, or the method for laminating sheets of materials together to from a package. Your article should answer the question “Have you ever wondered how we .

4. Write sevlral paragraphs describing a mechanism in operation; include a visual aict The mechanism might be a machine, or it might be a system, such as the procedure for hiring new personnel. Choose a mechanism you know well choose from this list: a sewing machine constructing a stitch light travelin through a camera lens, to the film the action as a bike shifts gear the steps in releasing the contents of a pressurized can . the retort process how an.air conditioner cools air how a solar furnace heats a room

5. Using the “EVA Hot Melt” report (pp. 196-197) as a model, describe a mechanism in your field.’.



The outline below shows the usual form for writing a description of a person in action. This approach will work for all such descriptions. A description of a person in action, analyzed in some detail follows the outline.

1. Introduction
2. Definition of process
3. Equipment needed
4. Major sequences of process
5. Body: Sequence of Person’s Activities (same as description of
operation, p. 187)


In .the introduction, writers define the process, explain the materials and the mechanisms necessary for performing the process, and list .the major steps in the process. A sample introduction to the process of layout planning follows.


Layout engineers plan the spatial elements of an industrial  plant In a process called layout planning. The four phases generally follow in sequence, but for the best results, the layout engineer may cause them to overlap in time.

The four phases are:
• Determining the location to be laid out
• Determining the overall layout
• Determining the detailed layout
• Determining the installation

Body: Sequence of a Person’s Activities

In the body, the writer describes the person’s actions in order, using one paragraph per step. Two notes on style seem appropriate. first when you write a process description, do not overdo the use of the imperative (command) voice. You are trying to describe, not order, the process. So in this type of writing it’s preferable to say, “We determine rather than “Determine . Second, try to give the·steps precise names. Notice that step’ 1 is named “Determining the relocation, a phrase that accurately describes a step. Do not give a step too concise a title, such as The Location?

Determining The Location

Determining the location for the new layout means to select the most Favorable conditions for obtaining the desired result. Determining the location does not necessarily mean to find a new site; more often, n means to decide whether to” reconfigure the current location or to move to some other available space. In a typical situation, the layout engineer must decide whether to use an available storage area or a newly acquired building

Determining The General Layout

Determining the overall layout means Recognizing the general arrangement of the area to be laid out. In this phase, the engineer works out the basic flow patterns not the product or materials in relation to the areas that have been allocated. This step allows the engineer to establish a rough idea of the general size, relationships, and configuration of each of the major areas to be laid out. Phase 2 is also called the block layout, the area allocation, or sometimes the rough layout.

Determining The Detailed Layout

Determining the detailed layout consists of locating each specific piece of machinery and equipment. In this phase, the engineer establishes the actual placement of each specific physical feature of the area to be laid out. The engineer makes detailed plans for each piece of machinery and equipment, and for aisles, storage areas, utilities, and service areas.

The engineer galss makes a detailed plan for the overall layout and for each of the departmental areas involved. The detailed Background layout is usually made of a board or sheet on which the engineer places  images of the individual machines or equipment. .

Determining The Installation

Determining;the installation means implementing’ the plans for the new space allocation. The engineer makes final plans  for installation, seeks the approval of the final plans by upper magnetometers new equipment, Andersen arranges for the necessary physical moves. The engineer does not physically ‘move the machinery but coordinates and supervises some other group, which does the actual installation.

Conclusion: ‘Optional

A conclusion is optional. If you choose to include one, you might discuss a number of topics, depending on the audience’s need, including the advantages. and disadvantages of the process.


Description is -an essential technique for technical writers. All description , ‘has common elements: the writer should define the process or mechanism. explain its function or. end goal, name its sub parts, name relevant details, arid explain its Significance. Three common types of description are describing mechanisms, describing operations, and describing people in action ..For each type of description the writer must consider the audience, select an.organizational principle, choose visual aids, and follow the usual form. Most script ions begin with an. introduction, which defines the topic and previews the sections to follow. In the body of the description, each section defines a stupor part by explaining it in detail, including its function or significance. To decide how much detail to include, writers consider. their audiences’ knowledge level and how they will use the document, In most descriptions a conclusion is optional.


models that follow describe mechanisms and processes. Based on what you know review them carefully to discover their strengths and’ weaknesses. Notice that the caliper example is really an informal memo  report  so the introduction contains materiel that differs  from the usual form.


1. Find a description of a mechanism in a manual or in a journal article. Determine its intended audience by analyzing the level of terminology. Also determine from the context the use the intended audience would make of it. Write a brief (one-page) memo to your instructor explaining your findings.

2. Write two one-paragraph descriptions of a mechanism that you know  well. If possible, use an item from your major. Otherwise, choose a common object like a kitchen utensil (measuring cups, whisk), a household tool (claw hammer, pliers), or an electronic appliance (tape deck, VCR). Write the first paragraph for a person who knows little about the mechanism and is curious; write the second for a knowledgeable person who is interested ‘in the mechanism’s advantages.

3. Either draw or photocopy a picture of a machine that you are familiar with (consumer manuals are a good source). Label all the parts that you think are significant. In class, exchange illustrations with a classmate. Interview your classmate to obtain details of the size, weight, color,’ material, as well as the use of your classmate’s machine. Spend about 15 minutes writing a short (two or three paragraphs) description of your classmate’s mechanism. After you have finished, critique each other’s paragraphs for effectiveness.

4. In class (or in small ‘groups, if your instructor’ wishes), compare a paragraph from “LayoutPlanning” (pp. 190-191) with a paragraph from “Skinfold Calipers” (pp. 194-195). How are the paragraphs organized? What is the function of the first sentence of each? Which paragraph seems more effective in conveying its message to the audience? Be prepared to make a brief presentation of yQur findings to the class.

5. Find a description of a process in a manual, a journal, or a textbook. Determine it~,intended audience by analyzing the level of terminology. Also determine from the context the use that the intended audience would make of the description. Write a brief memo explaining to your instructor whether or not the description would be suitable to assign to beginners.

6. Prior to class, find a brief (five to ten steps) set of instructions such as how to use a machine or system in the library. In class, rewrite the
instructions into a description of a person performing the process.

7. In one paragraph, describe a person performing a very common action, such as starting a car, putting on a shirt or a blouse, purchasing a ticket for a performance, or doing an exercise routine. Start with a statement of the goal or object of the action, then describe the steps the person rrlust take to complete the action.

8. Draw a flow chart, or a decision chart  of a process you know well. The process can be either a mechanism in operation or a person acting. Use a simple test or evaluation method in your field, or a simple procedure such as starting a computer. In class, exchange papers with another student and, for about 20 minutes, compose a draft that describes the process. Then interview each other to learn exact details and the goals of the steps. Revise the paper for the next class period.



The outline below shows the usual form of a description of a process that does not involve a person. This approach will work for all such descriptions. A process description, analyzed in some detail, follows the outline.

1. Introduction
2. Definition of operation
3. Principles(s) of operation
4. Major sequences of operation
5. Body: Description of operation
6. Sequence A
7. End goal of sequence
8. Detailed description of action
9. Sequence B (same as A)
10. Conclusion (optional)


The introduction to a process description contains general information that prepares the reader for the specific details that will follow. In the introduction you define ~e process, explain its principles of operation (if necessary), and preview the major sequences. The following introduction performs all three tasks.

Body: Description of the Operation

In the body of the paper write one paragraph for each step of the process. Each paragraph should begin with a general statement about the end goal or main activity. Then the remainder of the paragraph explains in more detail the action’ necessary to achieve that goal. Notice in the following example how each paragraph starts with an overview  a statement of purpose or end goal and how all the paragraphs are constructed in the settle pattern.


Transformation is the step in which the relatively large AC voltage (110 volts AC) is converted into a smaller AC voltage (12 volts AG). This conversion is done with a transformer, an electrical device with two parts: a primary coil and a secondary coil. The primary coil is basically several loops ct fine wire. The secondary coil is similar to the primary Coil, but it is thicker and has fewer loops. The large AC voltage (110
AC) flows into the primary coil of the transformer. When’  the AC passes through this coil, a magnetic field is produced, a phenomenon known as Faraday’s law. The magnetic field then passes through the secondary coil, producing a voltage in it (see Figure 3). The voltage produced in the secondary coil depends on the ratio of loops of wire between the coils with the correct number of loops in both the primary and secondary coils, the 110 volt AC converts into 12 volts AC.


Rectification is the step in which the small AC from the secondary coil of the transformer is converted into DC. This conversion  done with an electronic component known as a diode  A diode is like an electronic check valve; it only allows current to flow through it in one direction. When the AC (which by definition continually reverses in direction) is passed through a diode, only the top half (positive half) of the sinusoidal waveform is allowed to pass.through. The bottom. half (negative half) is absorbed by the diode The current leaving the diode.is traveling in only’ one direction and therefore fits the definition of DC. However. as you can see in.Figure 4. the DC leaving the diode ‘is quite “lumpy.” As a result. it is not very useful.


Conclusions to brief descriptions of operation are optional. At times writers follow the description with- a discussion of the advantages and disadvantages of the  process, ‘or with a brief summary, If you have a written relatively brief well.



Technical writers often describe processes. Methods of testing or evaluating, methods of installing, flow of material through a p’lant, the schedule for implementing a proposal, and the method for calculating depreciation are all exaQ1plesof processes. Manuals and reports contain many examples of process ,descriptions. Processes are usually one of two types: the operations of a mechanism or system that do not involve human activity, and the operations that do involve human activity. As with a mechanism description, the writer must consider the audience, select an organizational principle, choose visual aids, and follow the usual form for writing descriptions.

Consider the Audience

The knowledge level of audiences and their potential use of the document will vary. While most audiences for a process description have relatively little knowledge uf the process, they must often make a decision based on such a description. The process description is, in effect, vital background information for the decision. For instance, a plant engineer might propose a change in material flow in a plant because a certain step i~ inefficient, causing a bottleneck. To get the change approved, he or she would have to describe the old and new processes to a manager, who would use that description to make a decision about whether to implement the new process er not. Process descriptions also are used to explain in detail the implementation of a project. If a company plans to install a complicated piece of machinery in a plant, a careful schedule is written so that all affected parties understand what actions will occur at each step.

Select an Organizational Principle

The organizational principle for processes is chronological: the writer starts with the first action Dr step and continues in order until the last. Many processes have obvious sequences of steps, but others require careful examination in order to determine the most logical sequence. If you were describing the fashion cycle, you could easily determine its four parts (introduction, rise, peak, and decline). If, however, you had to describe the complex flow of material through a plant, you would want’ to base your sequence of steps on your audience’s knowledge level and intended use of the description. You might treat “receiving” as just one step, or you might break it into several steps, like “unloading,” “sampling,” and “accepting.” Your decision depends on how much your audience needs to know.

Choose Visual Aids

If your subject is a machine in operation, visuals of the machine in different positions will clarify the process. If you are describing a process that involves people, a flow chart can quickly clarify a sequence. For example, you might use j)le following flow chart to explain a hospital nutritionalassessment program.

Follow the Usual Form for Writing Descriptions

The process description takes the same form as the mechanism description: an introduction, which provides an overview, and the body, which treats each step in detail, usually one step to a paragraph. In each paragraph, first define the step, often in terms of its goal or end product, then describe it.




The outline below presents the usual fonn for writing a mechanism description. This basic approach, with slight variations, will work in most instances:

I. Introduction

A. Definition and purpose

B. Overall description (size, weight, shape, material)

C. Main parts

II. Body: Description of Mechanism

A. Main part A (definition followed by detailed description of size, shape, material, location, and method of attachment) B. Main part B (definition followed by overall description, then identification of subparts)

1. Subpart X (definition followed by detailed description of size, shape, material, location, and method of attachment)

2. Sub part Y (same as for sub part X)

3. Optional conclusion


The introduction gives the reader a framework for understanding the mechanism. In the introduction’ you should define the mechanism, tell its purpose, present an overall description, and preview the main parts. In the following introduction, the writer does all four:

To: Emily BroJn                                                           Date: July 18, 19XX
From: Steve V,andeWalle
Subject: Tablejep Paper Micrometer

This memo provides the information you requested at our July 17 meeting dealing with my department’s paper micrometer. A paper micrometer is a small measuring instrument used to measure the thickness of a piece of paper. The micrometer, roughly twice as large as a regular stapler , has four main parts: the frame, the dial, the hand lever, and the piston.

Body: Description of Parts

The body of the paper contains the detailed description. Usually you identify each main part with a heading, then describe it in a single paragraph. Each paragraph will follow the outline explained earlier in the section on The Common Elements of Description, p. 175. In the example below, notice that each section describes only one item. If necessary, you can divide a secnonmro subsections.

The Frame

The frame of the paper micrometer is a cast piece of steel that provides a surface to which all of the other parts are attached. The frame, painted gray, looks like the letter C with a large flcttdisk on the bottom and a round calibrated dial on top. The disk is 4112 inches in diameter and resembles a flat hockey puck. The frame is 5% inches high and 7112 inches long. Excluding the bottom disk, the frame is approximately 1V4 inches wide. The micrometer weighs 8 pounds.

The Dial

The dial shows the thickness 01 the paper. The dial looks like a watch djal except that it has only one moving hand. The frame around the dial is made of chrome-plated metal. A piece of glass protects the face of the dial in the same way that the glass crystal on a watch protects the face and hands. The dial, 6 inches in diameter and 7/8 inches thick, is calibrated in .001 inch marks, and the face of the dial is numbered every .010 inches. The hand is made from a thin, stiff metal rod, pointed on the end.

The Hand Lever

The hand lever, shaped like a handle on a pair of pliers, raises and lowers the piston. It is made of chrome-plated steel and attaches to the frame near the base of the dial. The hand lever is 4 inches lorg, V2 inch wide, and V4 inch thick. When the hand lever is depressed, the piston moves up, and the hand on the dial rotates. When the hand lever is released and a piece of paper is positioned under the piston, the dial shows the thickness of the paper.

The Piston 

The piston moves up and down when the operator depresses and releases the hand lever. This action causes the paper’s thickness to register on the dial. The piston is % inches in diameter, flat on the bottom, and made of metal without a finish. The piston slides in a hole in the frame. The piston can measure the thickness of paper up to .300 inches

Other Patterns for Mechanism Descriptions

Two other patterns fire useful for describing mechanisms: the function method and the generalized method. The Function Method One common way to describe a machine is to name its main parts and then give only a brief discussion of the function of each part. This function method is used extensively in manuals. The following paragraph is an example of a function paragraph.


The four function buttons, located under the liquid crystal display, work in conjunction with the function switches. The four switches are hertz (Hz), decibels (dB), continuity (c), and relative (REL). The hertz function can be selected to measure the frequency of the Input signal by pressing button 1. Press the button again to disable. The decibel function allows you to measure the intensity of the input signal, which is valuable for measuring audio signals. It functions the same as the hertz button. The continuity function allows you to turn on a visible bar o~the display, turn on an audible continuity signal, or disable both of them. The relative function enables you to store a value ‘as a reference value. For example, say you have a value of 1.09 volts stored: every signal that you measure with this value will have 1.00 volt subtracted from it.

The Generalized Method

The generalized method does not focus on a part-by-part description; instead the writer conveys many facts about the machine. This method of describing is commonly found in technical journals and in technical reports. With the generalized method, writers use the following outline Gordan 19-22, 35):
1. General detail
2. Physical description
3. Details of function
4. Other details

General detail consists of a definition and a basic statement of the operaticIn principle. Physical description explains such items as shape, size, arrea’ ance, and characteristics (weight, hardness, chemical properties, methods of assembly or construction). Details of function explain these features the mechanism:

how it works, or its operational principle its applications how well and how efficiently it works special constraints, such as conditions in the environment how it is controlled how long it performs before it needs service Other details include information about background marketing general information, such as who makes it The article on anti-static foam in Chapter 6 (p. 110) and the EVA hot melt model at the end of this chapter are examples of this kind of description.




The goal of a mechanism description is to give readers all the information they need to know about the mechanism. Obviously you can’t describe every part in minute detail, so you select various key parts and their functions. Most important you must plan the description before writing it. When you plan a description of a mechanism, you must consider the audience, select an organizational principle, choose visual aids, and follow the usual form for writing descriptions.

Consider the Audience

Consider the audience’s knowledge level and why they need the information. Both will determine how much detail you include. In the following mechanism description, the writer uses very specific detail to show an expert reader that the part exactly fulfills the specifications and then explains the significance of these details.

The IRU contains an Inertial Sensor Assembly (ISA), power supply, eight elecjfonic boards, and a chassis containing a motherboard. Its form and dimensions (7.60 in. high x 12.69 in. wide x 12.76 in. long) meet the requirements of ARINC 60010 MCU. With the implementation of second-generation electronics (14 boards reduced down to 8 boards), six empty electronic card slots are left for future growth. (Honeywell 3-10)

But in the following description, from a different document, the writer does not include any specific details, aiming instead at a reader who needs only a general understanding of the part:

The pump creates fluid flow within the system. The system  has a gear-type pump made of two components: a drive gear and a driven gear, both in a closely fitted housing. The drive  gear, which is powered by an electric motor, turns the driven gear ‘in the opposite direction. As the gears turn, they mesh at  a point in the housing between the inlet and the outlet ports. The fluid trapped between the teeth and the housing is pushed through the outlet port by atmospheric pressure due to the low pressurefreated by the rotation of the gears. This creates
fluid flow.

Select an Organizational Principle

You can choose from a number of organizational principles. For instance, you can describe an object from

• top to bottom (or bottom to. top)

• outside to inside (or inside to outside)

• most important to least important (or least important to most important)

For example, if you were going to describe a secretarial chair from top to bottom, you might start with the backrest, then go to the seat, and then move down to the casters. Or you could do the reverse. If you wished to describe it from most important to least important, you might start with the seat, then describe the backrest, and then the casters.

To make your decision, consider the audience’s potential use of your’ document. If the audience needs a general introduction, then an easy sequence, from top to bottom, is best. If your audience needs to know special details for secretaries’ safety and comfort, you might start with the caster system, which prevents tipping, then go to the adjustment system, which eases back strain.

An easy way to check if your organization is working is to look for “backtracking.” Your description should move steadily forward, starting
with basic definitions or concepts that the audience needs to understand later statements. If your description is full of sections in which you have to stop and backtrack to define terms or concepts, then your sequence is probably inappropriate.

Choose Visual Aids

Use visual aids to assist your description of a complex mechanism. The type of visual you select depends on the mechanism and the reader. H your readers need an overview of a secretarial chair so that they can see how each part is constructed, then you should use a drawing or photograph of the entire unit. If, however, they need to know how the backrest can be adjusted to a comfortable height, the overall drawing is useless. Instead, provide a drawing or photograph of the adjusting assembly behind the backrest.

Follow the Usual Form for Writing Descriptions

Generally, descriptions follow a similar form: an introduction or an overview followed by a body in which each part is described in turn (see pp. 180-181). Physical descriptions generally require no conclusion because a good description leaves nothing to conclude. Sometimes, however, you can place in a conclusion material that needs clarification but that does not fit elsewhere. If the operating principle of the mechanism, for instance, is complicated, you might explain it at the end of the description.




Regardless of the audience or purpose, all the descriptions you write should follow a general form: start with an overview, and add necessary details Gordon). For most descriptions, you should the following:

• Define the mechanism or process

• Explain its function or end goal.

• Name its sub parts.

• Give relevant details:

For mechanisms – size, shape, weight, material, method of attachment.

For processes quality or quantity of action, and effect of action. Explain the significance of the mechanism or process, if necessary. Read over the following description of a part (of a computer printer) and the accompanying annotations to see how the author explains the
part. Notice that the author starts with a definition and then adds details.

The paper advancement panel is a row of three buttons in a plastic rectangle. It allows the user to advance the paper out of the printer and to align the paper before printing. The panel is 3 inches long by 2 inches wide. It contains three %-inch by V2-inchsquare buttons that control the paper advancement. These paper advancement buttons are the on-line, line feed, and form feed buttons. The on-line button controls the power to the form feed and line feed buttons. When the on-line button is on, it allows the printer to print. When the on-line button is off, the user can activate the form feed and the line feed buttons. Tbe form feed advances the paper one full page; the line feed advances only one line ara time.

A description of a process works the same way. In the following example, the writer starts with a definition of the end goal of the process and then explains the steps and the significance

The quality chlick determines if the drawing is good enough to use. The qu?Jity control (QC) person inspects the drawing for proper standard drafting techniques and for adherence to company standards. He or she also determines whether the drawing has all the necessary information to manufacture the part. If no errors are found, the QC person signs off on the drawing, then sends it to manufacturing.





Description is a technique widely used in technical writing. In fact, you will probably describe something – machines, processes, or systems – in every report you write. Sometimes you will describe in intricate detail, and other times in broad outline. Regardless of the topic or the depth of detail, all descriptions share several common elements. ~is chapter explains those elements and shows you how to apply them when you describe a mechanism, an operation, and a process focused on a person.