The Dash, though often used improperly by hasty and incoherent writers,
may be introduced with propriety, where the sentence breaks off
abruptly; where a significant pause is required; or where there is an
unexpected turn in the sentiment; as, "If thou art he, so much respected
once--but, oh! how fallen! how degraded!" "If acting conformably to the
will of our Creator;--if promoting the welfare of mankind around us;--if
securing our own happiness;--are objects of the highest moment: then we
are loudly called upon to cultivate and extend the great interests of
religion and virtue."
A dash following a stop, denotes that the pause is to be greater than if
the stop were alone; and when used by itself, requires a pause of such
length as the sense only can determine.
"Here lies the great--False marble, where?
"Nothing but sordid dust lies here."