Avoiding Common Errors

of Punctuation

Punctuation marks are the traffic signs and signals placed along the reader’s road. They tell him when to slow down and when to stop, and sometimes they warn him of the nature of the road ahead. Traffic engineers do not always agree on what signs should be used and where they should be placed, and neither do writers or editors.

Theodore M. BernsteinThe Careful Writer

,

Punctuation rules are designed to have sentences be read one way.

Colon: a colon introduces a formal list, long quotation, equation, or definition.

Semi-Colon: a semi-colon either joins two independent clauses (closely linked in thought) or separates complex items in a list.

Dash: a dash acts as a parenthesis to separate items that cannot be separated by commas.

Comma: a comma separates details in a sentence.

A colon introduces a formal list, long quotation, equation, or definition.

We studied five types of marsupials: opossums, bandicoots, koalas, wombats, and kangaroos.

The laboratory growth of this crystal made possible a new astronomical tool: a gamma-ray detector with high-energy resolution.

In formal writing, what is on the left side of the colon should stand alone as a separate sentence.

Once the list ends, the sentence ends.

Although equations are separated by white space, they should be treated as part of the sentence.

To calculate the strain, , we used equation 1:

where is the stress estimated by FEPC and E is the modulus of elasticity of aluminum.

=E

(1),

Em-dashes act as parentheses to separate items that commas cannot

Because two isotopes of hydrogen—deuterium and tritium—are lightweight, can be produced easily, and require little energy, they are prime candidates to begin the fusion process.

After one year, we measured mirror reflectivity at 96 percent—a high percentage, but not as high as originally expected.

Because two isotopes of hydrogen (deuterium and tritium) are lightweight, can be produced easily, and require little energy, they are prime candidates to begin the fusion process.

After one year, we measured mirror reflectivity at 96 percent (a high percentage, but not as high as originally expected).

Commas separate introductory phrases and clauses.

After cooling the exhaust gases continue to expand.

After cooling, the exhaust gases continue to expand.

Using a comma after an introductory phrase depends on the situation.

In nine cases the people were infected by a rarestrain of the virus that did not cause AIDS.

(Placing a comma after “cases” is optional.)

When feeding a shark often mistakes undesirable food items for something it really desires.

(You need a comma after “feeding.”)

Commas separate parenthetical details.

X-ray backscatter systems, which are relatively inexpensive require the operator’s attention.

X-ray backscatter systems, which are relatively inexpensive, require the operator’s attention.

Commas set off contrasted elements. (These expressions often begin with “but” or

“not.”)

Examples:

The shark repellant was quite effective against Atlantic sharks, but ineffective against Pacific sharks.

Many injuries result from shark bumps, not shark bites.

Commas separate items in a list.

Discharges of these hazardous substances occurred through spills when loading vehicles, spills and over-spills when filling the tanks, leaks from supply pipes and corroded welds, rust holes and cracks in the seams of the tanks themselves.

Discharges of these hazardous substances occurred through the following: spills when loading vehicles; spills and over-spills when filling the tanks; leaks from supply pipes; and corroded welds, rust holes, and cracks in the seams of the tanks themselves.

How do you decide whether to use commas?

Think about whether your readers would trip if the comma weren’t there. (The purpose of commas is to eliminate ambiguities.)

In any case, be consistent in your use of commas. If you punctuate a sentence structure one way in the beginning of a paper, follow that style all the way through.

Language:the Way We Use Words

Concise

Familiar

Clear

Fluid

Precise

Forthright

wordwordwordwordwordwordwordwordwordwordwordwordwordwordword

wordword

word

word wordwordwordwordwordwordword

word

wordword

word wordword

Generalities that are not anchored with specifics are soon forgotten.

After recognizing some problems with the solar mirrors, we took subsequent corrective measures.

Trash

After finding that high winds (and not hail) had cracked the ten solar mirrors, we began stowing all mirrors in a horizontal position during thunderstorms.

For precise language, you should avoid over-specifying details.

The number of particular hydrocarbon combinations in our study is enormous. For example, the number of possible C20H42 is 366,319 and the number for C40H82 is 62,491,178,805,831.

The number of hydrocarbon combinations in our study is enormous. For example, the number of possible C40H82 is more than 62 trillion.

For precision, you must choose theappropriate level of detail.

Operations at the plant stopped momentarilybecause the thermal storage charging systemdesuperheater attemperator valve was replaced.

Operations at the plant stopped for 1.5 hoursso that a valve in the thermal storage systemcould be replaced.

R.I.P.

Complex wording buries ideas.

This study will consider why current solar energysystems, such as Solar One, have not reached thecommercial stage and will find out what steps we can take to make these systems commercial.

The goal of this study is to develop a commerciali-zation strategy for solar energy systems by analyzingfactors impeding early commercial projects (i.e., SOLAR ONE) and by identifying the potential actionsthat can facilitate the viability of the projects.

Stacking adjectives before nouns swallows the ideas

Solar One is a solar-powered pilot plant located near Barstow, California. Solar One produces 10 megawatts of electricity by capturing solar energy in a central receiver design.

Solar One is a 10 megawatt solar thermal electric central receiver Barstow power pilot plant.

Complex sentences misdirect readers

The goal of the work was to confirm the nature of electrical breakdown of nitrogen in uniform fields at high pressures and electrode gaps which approach those obtained in engineering practice, prior to the deter-mination of the processes which set the criterion for breakdown in the above-mentioned gas in uniform and non-uniform fields of engineering significance.

At high pressures (760 torr) and typical electrode gapdistances (1 mm), the electrical breakdown of nitrogen was studied inuniform fields.

The more muddled the original, the more revisions are needed to streamline it

At high pressures (760 torr) and typical electrode gapdistances (1 mm), the electrical breakdown of nitrogen was studied inuniform fields.

In our study, we examined the electrical breakdown of nitrogen in uniform fields. For these experiments, the electrode gap distances were typical (1 mm), while the pressures were relatively high (760 torr).

One measure for the complexity of the writing is the Gunning Fog Index

In the index, the complexity of the writing depends on(1) the lengths of sentences(2) the lengths of words

Desired index values forscientific writing are 10-12:New York Times (11)Scientific American (12)

Fi = 0.4 ((Nw / Ns )+ Plw ) Nw = number of words in a typical paragraph Ns = number of sentences in the paragraph Plw = percentage of long words in the paragraph

An ambiguity is a group of words that can have more than one meaning

We examined neat methanol and ethanol and methanol and ethanol with 10% water.

We examined four fuels: neat methanol, neat ethanol, methanol with 10% water, and ethanol with 10% water.

Ambiguities occur for many reasons

?????????

???????As light hydrocarbons evaporate the oil vapor pressure falls.

Although engineers realized the design flaws in the Titanic soon after its sinking in 1912, the reasons for the severe damage inflicted by the iceberg remained a mystery until its discovery in 1985.

????

The proposed schedule is discussed below for the next four years.