Punctuation Of The Compound Sentence
1. The rain descended, the floods came, and the winds blew and beat upon that house; and it fell not; for it was founded upon a rock.
2. As the region now stands higher than before, the rivers tend to wear down their valleys to the new level of the sea at their mouths; the valley sides waste away; and thus the valleys slowly become wider; but the streams cannot wear the valleys deeper than the sea at their mouths.
The sentences above show all the punctuation that is peculiar to compound sentences.
Observe in the first sentence that the first three members being short and closely connected are separated by commas. The remaining members are separated by the semicolon, because they are less closely connected.
In the second sentence as the comma is used to sepa-rate the clause from the first statement the semicolon is used to show the distinction between the principal statements.