LXXIV. The apostrophe is used to indicate that some letter or letters of a word are left out.
"E'er" for "ever," "can't" for "cannot," "don't" for "do not," "'gin" for "begin."
The apostrophe is not used when the word, though contracted in the middle, retains its original pronunciation; as "Dr." or "Mr." But it is used where the contraction is at the end of the word: "tho'," "Peterboro'."
LXXV. The apostrophe marks the possessive case of nouns. The following rules determine where it is to be placed:
Nouns in the singular number—
(1) The letter "s" is added, and the apostrophe is placed before it.
The king's abode. A patriot's reward.
(2) If the nominative singular of the noun ends in "s," another "s" is not added if the repetition of hissing sounds would be displeasing to the ear. The apostrophe is then placed at the end of the word.
Hercules' club. Augustus' dignity.