THE HYPHEN
Authorities differ in regard to the use of the hyphen. However, there are two rules which always hold good: (1). The hyphen is used to separate compound adjectives; (2). The hyphen is used to show, at the end of a line, that a word has been divided. (Such a word must be divided between syllables.) In other cases, when you cannot decide whether or not to use a hyphen, consult the dictionary used in your school. It is much less frequently used than formerly.
RULES FOR SPELLING
I. Formation of Possessives
1. The following list is made up of words in the singular number. To form the possessive, add an apostrophe and "s."
horse's head
man's coat
girl's dress
boy's shoes
soldier's uniform
child's laugh
sheep's wool
sister's hat
2. The following list is made up of plural nouns that do not end in "s." To form the possessive, add an apostrophe and "s."
children's clothes
men's shirts
women's praise
gentlemen's plans