Omission of that
That can sometimes be omitted from restrictive relative clauses, but this omission is not recommended:
Correct The model they analyzed is the most realistic one studied.
Better The model that they analyzed is the most realistic one studied.
Articles
Indefinite articles a and an
• The indefinite article a precedes a word beginning with a sounded consonant, and an precedes a word beginning with a vowel sound.
• Whether a or an should precede an abbreviation or acronym depends not on its initial letter but on how the author expects it to be read (Bernstein 1981). For example, most people read "M.A." as letters rather than as "Masters of Arts," so "an M.A. degree" is appropriate. Likewise, we prefer "an NACA airfoil." However, "NASA" is not usually read as letters, so we prefer "a NASA airfoil."
Articles with coordinate adjectives
Whether or not articles are repeated before coordinate adjectives affects meaning (Rowland 1962).
• If coordinate adjectives each refer to different things or persons, articles are repeated when the modified noun is singular and are not repeated when the modified noun is plural:
Wrong The transverse and shear strain is calculated for each specimen. (two strains)
Correct The transverse and the shear strain is calculated for each specimen.
Or The transverse and shear strains are calculated for each specimen.
• If coordinate adjectives refer to one thing or person, the article is not repeated:
Wrong A more nonlinear and a lower stress-strain curve resulted from the test. (one curve)
Correct A more nonlinear and lower stress-strain curve resulted from the test.
Omission of articles
There is a trend in modern writing, particularly journalism, to omit articles. Langley has traditionally preferred this "elliptical style" for symbol lists, figure captions, headings, and titles:
u ratio of [the] wing mass to [the] mass of air in [a] truncated cylindrical cone enclosing [the] wing .
Verbals
The three types of verbals are the gerund (verb ending in ing used as a noun), the participle (verb used as an adjective), and the infinitive (verb preceded by to used as an adverb, adjective, or noun).
Coordinate Gerunds and Infinitives
Grammar authorities all remind us that a gerund takes a singular verb:
Substituting the expression into equation (2) yields ...
But these authorities are silent on the number of a verb following coordinate gerund subjects:
Substituting this expression in equation (2) and simplifying the result yields . . .
• We prefer a singular verb if a series of actions expressed by coordinate gerunds can be considered a single process.
• Likewise, the prepositions should not be repeated before coordinate gerunds or infinitives that express a process (Rowland 1962):
The following expression results from substituting equation (1) into equation (2), integrating by parts, and taking the limit.
The test procedure was to combine the samples in a large vat, stir the mixture, and then withdraw samples for analysis.
Idiom Requiring Gerund or Infinitive
Whether a particular verb should be followed by an infinitive or a gerund phrase is a matter of idiom, for example,
Correct The display helped the pilot to cope with the increased work load.
Wrong The display aided the pilot to cope with the increased work load.
Although the meaning of these two sentences is the same, changing the verb changes the verbal required by idiom:
Correct The display aided the pilot in coping with the increased work load.
Dangling Verbals
An infinitive, gerund, or participle dangles when the agent of the action that it expresses is not clear.
Some authorities (IRS 1962; Tichy and Fourdrinier 1988) consider an introductory gerund or infinitive phrase to dangle when it does not modify the subject:
When using a nonaligning pitot static tube, the total velocity component cannot be exactly measured because of the swirl component.
To predict the thrust and power coefficients of the propeller, the aerodynamic coefficients must be provided.
Rowland (1962) considers such gerund phrases acceptable because "they are employed so frequently in technical writing that they may be said to be idiomatic." The same can be said of introductory infinitive phrases. These introductory phrases are clearly adverbial because no one would attribute their action to the subject. Note that the verbs in the above sentences are in passive voice, so that an unknown agent can be supplied for the verbals' actions. When the verb is in active voice, the verbal tends to dangle:
When using a nonaligning pitot probe, the swirl component precludes exact measurement of total velocity.
• Introductory gerund and infinitive phrases do dangle when they modify a noun in the sentence other than the subject:
Wrong When using a nonaligning pitot static tube, total velocity cannot be measured exactly by the investigator because of the swirl component.
Correct When using a nonaligning pitot static tube, the investigator cannot exactly measure total velocity because of the swirl component.
Although Rowland justifies introductory adverbial gerund and infinitive phrases because they are idiomatic and clearly adverbial, he does not extend this argument to participles. He condemns dangling participles as "slovenly English" and "weak constructions that should be replaced by more robust phrasing." Are dangling participles slovenly English? Or, like the dangling gerund, are they becoming idiomatic?
Absolute participles
A class of apparently dangling participial phrases that have become idiomatic are absolute participles (Bernstein 1981). They have no antecedent and none is intended; that is, they are indefinite, for example,
The density mode is preferred provided that optical properties are measured.
Given a variable factor, the fluctuating flow components can be calculated from equations (31) to (38).
Either the density mode or the pressure mode can be used, depending on whether supporting optical measurements or probe measurements are made.
Other idiomatic absolute participles are
generally speaking concerning
considering regarding
judging beginning
Such constructions must be truly absolute, with no antecedent in the sentence. In the following sentence, what appears to be an absolute participle is actually dangling:
Dang. partic. An arbitrary factor controls the accuracy of the calculation depending on pressure fluctuations.
Better A variable factor depending on pressure fluctuations controls the accuracy of the calculation.
Technical writing often contains absolute participles that are not idiomatic, for example,
The arbitrary factor can be assumed to be small and therefore can be neglected, yielding a first-order solution.
Such a participle might be justified by arguing that it is an absolute adjective construction modifying the whole sentence. However these participles can sometimes be made adverbial:
The arbitrary factor can be assumed to be small and therefore can be neglected to yield a first-order solution.
Sometimes a participle at the end of a sentence is not absolute, but actually modifies the subject in a nonrestrictive way:
Nonrestrictive partic. Increasing the leak area caused the boundary layer to attach, thus decreasing heat transferred to the cove interior.
The MLA's Line by Line (Cook 1985) does not object to such placement of a participle. However, these participles can usually be changed to a compound predicate:
Compound predicate Increasing the leak area caused the boundary layer to attach and thus decreased heat transferred to the cove interior.
Do not confuse absolute participles with nominative absolute constructions, which are perfectly grammatical. Nominative absolutes have their own subjects and modify the whole sentence:
Dang. partic. Maraging steels are promising for cryogenic service, having hardness at -320°F of 38Rc.
Nom. abs. Maraging steels are promising for cryogenic service, their hardness at -320°F being 38Rc.
Adverbial participles
What appears to be a dangling participle is left when the preposition by is dropped from an adverbial gerund phrase. These "adverbial participles" may appear after the verb or at the beginning of the sentence:
Adverb. partic. The logarithmic derivative is obtained using this least squares representation.
Gerund phrase The logarithmic derivative is obtained by using this least squares representation.
Adverb. partic. Neglecting the dependence of n on Reynolds number, the results of figure 11 can be used to estimate n.
Gerund phrase By neglecting the dependence of n on Reynolds number, the results of figure 11 can be used to estimate n.
Adverb. partic. Substituting equation (34) instead of equation (14), the terms for the fluctuating modes can be rewritten.
Gerund phrase By substituting equation (34) instead of equation (14), the terms for the fluctuating modes can be rewritten.
Restoring by to these phrases adds very little to the above sentences. The participles in these sentences clearly modify the verbs; thus their meaning is clear. But participles are, by definition, adjectives, so that adverbial participles are not grammatical. Also there are methods of revising adverbial participles other than restoring their by. In the following sentences, stronger constructions replace the participial phrases:
Prep. phrase The logarithmic derivative is obtained from this least squares representation.
Prep. phrase With the dependence of n on Reynolds number neglected, the results of figure 11 can be used to estimate n.
Gerund subject Substituting equation (34) instead of equation (15) allows the terms for the fluctuating modes to be rewritten.
Dangling participles
When a participle genuinely appears to modify the wrong noun, truly dangling and thus much more offensive:
Dang. partic. Using a nonaligning pitot probe, the swirl cormponent precludes exact measurement of total velocity.
Better When a nonaligning pitot tube is used, the swirl component precludes exact measurement of total velocity.
Dang. partic. The shock is essentially normal near the body, producing subsonic flow.
Better Near the body is an essentially normal shock producing subsonic flow.
Dang. partic. Encouraged by these results, a new research effort was begun.
Better Encouraged by these results, we began a new research effort.
Recommendations
• When an introductory gerund or infinitive phrase is clearly adverbial, we consider its use idiomatic and therefore we do not consider it dangling.
Although no writing authorities now claim that adverbial participles and nonidiomatic absolute participles are becoming acceptable in technical writing, such participles are widely used and well understood. Forbidding their use is perhaps like forbidding the tide to rise. These participial constructions are certainly not grammatical, but they are rarely misunderstood.
• So long as an adverbial or absolute participle does not appear to modify the wrong noun, it is acceptable, but not encouraged.
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