Grammatically Correct: The writer's essential guide to punctuation ...

PUNCTUATION
Several of the neighbors-the Walkers, Gold bergs and Millhouses­
started a petition to get rid of the Boylstons' rooster.
The more subjective measures-the patients' energy levels, health
outlooks and emotional well-being-tended to correlate more highly
with the charts than did the objective measures.
In another role, dashes act much like parentheses. The difference
is that their effect is usually to emphasize a digression rather than
subsume it. In general, text enclosed by dashes is more integral to
the sentence than text enclosed by parentheses. As with parentheses,
the digressive text may or may not be grammatically congruent
with the rest. (See "Parentheses" on page 144.)
[The hair was] grey at the root, the rest dyed a vivid metallic orange.
Dirk pursed his lips and thought very deeply. He didn't need to think
hard in order to realise who the hair belonged to-there was only one
person who regularly entered the kitchen looking as if her head had
been used for extracting metal oxides from industrial wastes-but he
did have seriously to consider the implications of the discovery that
she had been plastering her hair across the door of his fridge.
It meant that the silently waged conflict between himself and his
cleaning lady had escalated to a new and more frightening level. It
was now, Dirk reckoned, fully three months since this fridge door had
been opened, and each of them was grimly determined not to be the
one to open it first. ...
-DouGLAs ADAMS, The Long Dark Tea- Time of the Soul
... I am now living, for economy's sake, in a little town in Brittany,
inhabited by a select circle of serious English friends, and possessed
of the inestimable advantages of a Protestant clergyman and a cheap
market.
In this retirement-a Patmos amid the howling ocean of Popery
that surrounds us-a letter from England has reached me at last. I find
my insignificant existence suddenly remembered by Mr. Franklin Blake.
My wealthy relative-would that I could add my spiritually-wealthy
relative!-writes, without even an attempt at disguising that he wants
something of me. The whim has seized him to stir up the deplorable
scandal of the Moonstone; and I am to help him by writing the account
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