This section is from the book "Two Years' Course In English Composition", by Charles Lane Hanson. Also available from Amazon: Two Years' Course In English Composition.
Although the semicolon is not much used by young writers, it is sometimes indispensable, and we must therefore become familiar with its different functions.
XX. The semicolon separates short clauses which, though grammatically independent, are so closely connected in meaning that they naturally form a single sentence.
The Scot was fair-haired and blue-eyed; the Saracen was dark in coloring.
Those whose backs were turned wheeled round; all the others raised their heads; three waiters whirled about on their heels like tops; the two women at the desk gave a jump, then turned completely round, like automata obedient to the same crank.
XXI. The semicolon separates two or more phrases or clauses which depend upon another clause.
All that I wish is, that he may cease to distress his mind about other people's affairs; that he may give up the fruitless attempt to promote the good of his neighbors; that he may remain quietly at home; that he may long enjoy on his paternal lands a green, an honorable, and a merry old age.
XXII. The semicolon is frequently used to separate the clauses of a compound sentence, when such clauses contain commas.
At high tide, and at high tide only, the sailing is delightful, as there are a great many square miles of sheltered water to cruise upon; but at low tide, except in three small channels, there is no sailing.
108. Copy the following sentences; insert semicolons wherever they are needed, and point out their value.
1. He was courteous, not cringing, to superiors affable, not familiar, to equals and kind, but not condescending or supercilious, to inferiors.
2. In taking revenge, a man is but even with his enemy but in passing it over, he is superior.
3. Some said that Dolph Heyliger watched in the haunted house with pistols loaded with silver bullets others, that he had a long talk with a specter without a head others, that Doctor Kipperhausen and the sexton had been hunted down the Bowery lane, and quite into town, by a legion of ghosts of their customers.
4. To be honest, to be kind to earn a little and to spend less to make upon the whole a family happier by his presence to renounce where that shall be necessary, and not to be embittered to keep a few friends, but these without capitulation above all, on the same grim conditions, to keep friends with himself - here is a task for all that a man has of fortitude and delicacy.
 
Continue to: