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Choosing the Right Word
Water is comprised of hydrogen and oxygen.Because "comprise" literally means to embrace or to include, the above sentence is imprecise. A precise way to write this sentence is
Water is composed of hydrogen and oxygen.
For a more detailed list see Appendix B.
The problem centers around the drying and aging of the bloodstain.The phrase "centers around" makes no physical sense. What the writer wants is either "centers on" or "revolves around."
The problem revolves around the drying and aging of the bloodstain.
gas discharge: any one of the three steady states of the electrical breakdown process. These three steady states are the Townsend, glow, and arc.To use these two terms as synonyms is imprecise language. The first term is a steady state. The second term is a transition. However, in the first sentence of a recent journal article, a scientist tossed these terms around as if they were synonyms:
The last decade has seen a rapid development of new techniques for studying the enormously complex phenomena associated with the development of sparks and other gas discharges.Because a "spark" is not a "gas discharge," this sentence is imprecise. More important, because this sentence is the first sentence of the article, this imprecision undercuts the article's authority. Why did the scientist make this mistake? Given that the article was a review article and that the journal had solicited the scientist to write it, the scientist most likely didn't make the mistake because he didn't understand the vocabulary. He probably made the mistake because he was concentrating on the rhythm of the sentence rather than on the meaning. In other words, he wrote as if being fluid in the sentence was more important than being precise--something appropriate for poetry perhaps, but not for scientific writing.
Mixed convection is a combination of natural and forced convection. Two dimensionless numbers in the correlations for mixed convection are the Grashoff number and the Reynolds number. The Grashoff number (for free convection) is a measure of the ratio of buoyant to viscous forces, and the Reynolds number (for forced convection) is a measure of the ratio of inertial to viscous forces.Why did the engineer use "free convection" instead of "natural convection" in the third sentence? This synonym substitution added nothing to the discussion and only served to confuse readers unfamiliar with the vocabulary of heat transfer.
The turbulence in the flow enhances the drag by more than 20 percent.Because drag was an undesired quantity in this example, the engineer should have chosen a verb with a neutral or negative connotation ("enhance" has a positive connotation). Note that the denotation of "enhance" is also inappropriate here. To enhance something is to make an incremental change, but 20 percent is not incremental. A better word choice would have been either "increase" (neutral connotation) or "exacerbate" (negative connotation).
The turbulence in the flow increases the drag by more than 20 percent.
Choosing the Right Level of Detail
After recognizing the problems with the solar mirrors, we took subsequent corrective measures.What were the problems with mirrors? What were the solutions? How many mirrors were damaged? This entry raises questions, but does not address them. Given that the field of solar mirrors cost over $40 million, this entry in the progress report did not satisfy the Department of Energy. A more precise entry to the report would have been as follows:
Our last progress report (March 1985) discussed the damage to ten solar mirrors during a February thunderstorm. The question arose whether high winds or hailstones had cracked those mirrors. Now, after finding that high winds had caused the cracks, we have begun stowing all solar mirrors in a horizontal, as opposed to vertical, position during storms.
Our new process reduces emissions of nitrogen oxides from diesel engines and industrial furnaces.Replacing this generality with a specific detail gives your audience something concrete to remember. Take a lesson from fiction writing. Good fiction writers rely on specific details to create scenes because good fiction writers know that specific details are what readers remember.
Our new process eliminates 99 percent of nitrogen oxide emissions from diesel engines and industrial furnaces.Better yet, by grounding that detail (99 percent reduction), you insure that your audience understands its importance.
Our new process eliminates 99 percent of nitrogen oxide emissions from diesel engines and industrial furnaces. Previous processes have, at best, reduced nitrogen oxide emissions by only 70 percent.
The average house in the area has a radon level of 0.4 pico-curies per liter.Without a general qualifier, the audience is left with the question, How dangerous is 0.4 picocuries? That kind of writing is not only weak, but irresponsible. Revision gives
The average house in the area has a radon level of 0.4 pico-curies per liter, which is considered low by the EPA [Lafavore, 1987]. Levels between 20 and 200 picocuries per liter are considered high, and levels above 200 picocuries per liter are considered dangerous. For reference, the average radon level in outdoor air is about 0.2 picocuries per liter.
The number of particular hydrocarbon combinations in our study is enormous. For example, the number of possible C20H42 is 366,319 and the number of C40H82 is 62,491,178,805,831.What was the purpose of including these two numbers? The chemist wanted to show the extent of his calculations. However, were all those digits necessary? Also, because the second number was so much larger than the first number, was the first number necessary? A more precise paragraph would have been as follows:
The number of hydrocarbon combinations in our study is enormous. For example, the number of possible C40H82 is over 60 trillion.This revision achieves the desired result--showing the extent of the calculations--without making the audience wade through undesired numerals.
Consider another example, this one from a progress report about a solar power plant:
Operations at the plant stopped momentarily because the thermal storage charging system desuperheater attemperator valve was replaced.The name "thermal storage charging system desuper-heater attemperator valve" is a problem. For one thing, when written as a single noun phrase, it is difficult to read. For another thing, the report's readers (plant managers) did not know exactly what this particular valve was. All the readers knew about this valve was that it was in the thermal storage system. For that reason, a more appropriate level of accuracy would have been as follows:
Operations at the plant stopped for 1.5 hours so that a valve in the thermal storage system could be replaced.In this revision, the location of the valve was made less specific, while the time that the plant was down was made more specific. This report's readers cared more about how long the plant was down than about which particular valve was leaking.
A 1-mm diameter, 656-nm beam with uniform intensity across the beam was produced by using a wavelength/polarizer combination to split off part of the 532-nm output from the Nd:YAG laser to pump a second dye laser (Laser-Ray LRL-2, also operated with the DCM dye) with a side-pumped configuration for the final amplifier, and selecting the central portion of the collimated beam with an aperture.There are just too many details in this one sentence. Are all these details necessary? Couldn't the physicist have spread these details over several sentences? Better still, couldn't the physicist have placed the secondary details (such as beam wavelength and manufacturer's name) in an illustration? Scientists and engineers sometimes worry so much about telling readers everything that they end up not informing readers of anything.
The fuel pellets used in inertial confinement fusion are tiny, the size of BBs, but they are potentially the most powerful devices mankind has ever known. If we can compress the fuel in the pellets to a plasma, the fuel's deuterium and tritium atoms can overcome their mutual electrical repulsion and fuse into helium atoms, giving off energy (E = mc2). The power needed to ignite fusion in the pellets is 100 trillion watts; however, the power released from the fusion is one hundred times that much.This paragraph informs; it informs because the scientist selected the most important details about the pellets. Because scientific writing is compressed, you have room for only the most important details. Make them count.
Bennett, A., Literary Taste and How to Form It (London: George H. Doran Publishers, 1909).
LaFavore, M., Radon, the Invisible Threat (Pennsylvania: Rodale Press, 1987).
Last updated 1/99
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