Here was should be were.
154. Coördination and Subordination.—The third error in grammatical construction, failure to coördinate or subordinate sentences and parts of sentences properly, cannot be treated with so much sureness as the two preceding faults; yet certain definite instruction may be given. And, but, for, or, and nor are called coördinating conjunctions; that is, they are used to connect words, phrases, and clauses of equal rank. If one uses and to connect a noun with a verb, or a past participle with a present participle, or a verb in the indicative mood with one in the subjunctive, he perverts the conjunction and produces a consequent effect of awkwardness or lack of clearness in the sentence. Look at the following:
The sister residing in Albany, and who is said to have struck one of the visiting sisters, followed them into the sick room.
In this sentence and is used to connect the participle residing with the pronoun who, and the consequent awkwardness results. This is the much condemned and who construction. Likewise, in the next sentence:
Five hundred persons saw two boys washed from the end of Winter's pier and drowning in twenty feet of water at noon to-day.
And is here used to connect the past participle washed with the present participle drowning, and the sentence is thereby rendered clumsy.
155. Clauses Unequal in Thought.—An equally great inaccuracy is the attempt to connect with a coördinate conjunction clauses equivalent in grammatical construction, but unequal in thought value. Other things being equal, the ideas of greatest value should be put into independent clauses, the ideas of least value into dependent clauses or phrases. Other things being equal, be it understood, for by a too strict observance of this rule one may easily make the sentence ludicrous. Take the following as an illustration:
We were to raid the hall precisely at midnight, and we set our watches to the second.
Here the thought-value of the two clauses is not equal, no matter how the writer may attempt to make it seem so by expressing the ideas in clauses grammatically equal. The second clause contains the main idea; so the first should be subservient. Thus:
As we were to raid the hall precisely at midnight, we set our watches to the second.