Early editions of the Encyclopedia Britannica accepted Noah’s ark as real, to the point of discussing how the animals were arranged and fed:

Bishop Wilkins computes all the carnivorous animals equivalent, as to the bulk of their bodies, and their food, to 27 wolves; and all the rest to 280 beeves. For the former, he allows 1825 sheep; and for the latter, 109,500 cubits of hay; all which will be easily contained in the two first stories, and a deal of room to spare.

That’s from the 1797 edition. By 1860, realizing that an ark couldn’t possibly accommodate all the world’s species, Britannica suggested that the flood had covered only the parts of the earth inhabited by men. By 1911 it was describing the whole story as myth — and in 1960 it remarked on the “many ingenious and curious theories” that had once been advanced to support the story.