OBS. 3.—The question here is, Which is the most correct expression, “While the bridge was building,”—“While the bridge was a building,”—or, “While the bridge was being built?” And again, Are they all wrong? If none of these is right, we must reject them all, and say, “While they were building the bridge;”—“While the bridge was in process of erection;”—or resort to some other equivalent phrase. Dr. Johnson, after noticing the compound form of active-intransitives, as, “I am going”—“She is dying,”—“The tempest is raging,”—“I have been walking,” and so forth, adds: “There is another manner of using the active participle, which gives it a passive signification:[266] as, The grammar is now printing, Grammatica jam nunc chartis imprimitur. The brass is forging, AEra excuduntur. This is, in my opinion,” says he, “a vitious expression, probably corrupted from a phrase more pure, but now somewhat obsolete: The book is a printing, The brass is a forging; a being properly at, and printing and forging verbal nouns signifying action, according to the analogy of this language.”—Gram. in Joh. Dict., p. 9.
OBS. 4.—A is certainly sometimes a preposition; and, as such, it may govern a participle, and that without converting it into a “verbal noun.” But that such phraseology ought to be preferred to what is exhibited with so many authorities, in a preceding paragraph, and with an example from Johnson among the rest, I am not prepared to concede. As to the notion of introducing a new and more complex passive form of conjugation, as, “The bridge is being built,” “The bridge was being built,” and