Auk
2 of the 7 encyclopedias on this shelf carry an entry for Auk. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a member of the large group of diving birds. The auk is related to the murres, puffins, grebes, and loons. It is remarkable for the shortness of its wings, which it employs as fins or paddles for swimming under water. It is remarkable also for the position of the legs, which are placed so far backward that the bird walks with difficulty, and is obliged to maintain an upright attitude. It has a much compressed bill, so sharp along the ridge as to resemble the edge of a knife. The auks are sea-birds. They are wonderful divers. They catch fish, and gather shell fish at the bottom of the sea. They nest in colonies on islets or on the rocky shores of the northern part of the northern hemisphere . Auks lay but one egg in a season. There is no attempt at nest building. The female holds the egg above her webbed feet between the thighs. There are several species of auks. The razor-billed auk is the largest existing species. It is about seventeen inches long, blackish above, with a large white spot before the eye. The sides of the neck and throat are seal brown; belly, white. It is very common on the coasts of Britain. Its eggs are considered a delicacy. On the coast of Labrador the birds are killed for their feathers; and in some places their flesh is used for food. It is a fierce bird, and, if seized, will hold on to the hand with its bill until it is killed. The auk of which most has been written is the great auk. This bird was shaped somewhat like a loon, with black upper parts; sides of the upper parts and throat silvery brown; under parts silvery white. Length, thirty inches--the size of a goose. It was unable to fly. Its wings were shaped for diving flippers. It lived on fish, and ranged from Massachusetts and Ireland along the coasts and islands to the Arctic Circle . Its annual migrations were made wholly by swimming. It was hunted so zealously for oil, flesh, and feathers that, in spite of enormous numbers, no living auk has been seen since 1842. Some seventy specimens and a number of eggs have been preserved in museums. An egg is reported to have brought $1,000 in 1906 at a London auction. Four auks frequent our Pacific Coast. One, the least auklet, has the "bulk of a small, thinly-feathered screech owl." 2026 Editor's Note: The entry writes of auks as living birds, but the greatest of them was already doomed: the flightless great auk , the original 'penguin,' was hunted mercilessly, and the last known pair was killed in Iceland in 1844. Its extinction became a rallying symbol for the bird-protection movement that followed. (Ed: BR 2026-06-30)
Collier's New Encyclopedia (1921)
the name given to several sea birds, especially the great and the little auk. The great auk is the alca impennis of Linnæus. Its bones left behind show that it was formerly abundant on the shores of Iceland, Greenland and Denmark. The little auk of Pennant and others, called also the common rotche, and the little white and black diver is the mergulus melanoleucos of Yarrell's "British Birds," the M. alle of Carpenter and Dallas, and the alca alle of Linnæus . It has the breast, the belly, a dot above the eyes, and a stripe on the wing, white; the rest of the plumage black. Its length is 9 inches, and the extent of its wings 16. Its dimensions are thus about those of a large pigeon. It nestles in holes or crevices on the bare rocks , laying one bluish-green egg. It is abundant in the Arctic seas. It is found also in Great Britain.