I. All clauses are either independent or subordinate. A clause is subordinate if it is used as a part of speech (noun, adjective, or adverb); otherwise, it is independent ([§ 46]).
II. Coördinate means “of the same rank” in the sentence ([§ 46]).
1. Two or more independent clauses in the same sentence are manifestly coördinate.
- The fire blazed and the wood crackled. [Two declarative clauses.]
- What is your name, and where were you born? [Interrogative clauses.]
- Sit down and tell me your story. [Imperative clauses.]
2. Two or more subordinate clauses are coördinate with each other when they are used together in the same construction,—as nouns, adjectives, or adverbs.
Such a group may be regarded as forming one compound subordinate clause.
- The truth is, that I have no money and that my friends have forsaken me. [Noun clauses.]
- The Indians, who were armed with long lances, and who showed great skill in using them, made a furious attack on the cavalry. [Adjective clauses.]
- When he had spoken, but before a vote had been taken, a strange tumult was heard in the outer room. [Adverbial clauses.]
In the first example, we have a compound noun clause; in the second, a compound adjective clause; in the third, a compound adverbial clause.
3. Coördinate clauses are either joined by coördinate conjunctions (and, or, but, etc.), or such conjunctions may be supplied without changing the sense ([§ 362]).
The good-natured old gentleman, who was friendly to both parties, [AND] who did not lack courage, AND who hated a quarrel, spoke his mind with complete frankness.