North Sea
2 of the 7 encyclopedias on this shelf carry an entry for North Sea. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
or GERMAN OCEAN, that portion of the Atlantic Ocean extending from the Straits of Dover to the Shetland Islands, bounded on the E. by Norway and Denmark; on the S. by Hanover, the Netherlands, Belgium, and France, and on the W. by the the British Islands; length 700 miles, breadth 420 miles. It communicates with the Atlantic by the Straits of Dover and Pentland Firth, and with the Baltic by the Skagerrack, the Cattegat, the Sound, and the Great and Little Belts. It receives the waters of the Elbe, Rhine, Weser, and Scheldt, on the E., and the Thames, Ouse, Humber, Tyne, Tweed, Forth, and Tay on the W. Navigation is very difficult and dangerous, owing to the sand banks along the English coasts, and extending N. E. from the Firth of Forth, and one N. W. from the mouth of the Elbe, besides the variety of currents, which generally show a tendency toward the N. E., owing to the prevalence of the S. W. winds. The influence of tidal currents of the Atlantic is felt in the North Sea so as to cause a rise of 20 feet in the estuary of the Humber. The fisheries of the North Sea are important, and employ many thousands of people. The North Sea was a principal zone of naval authority during du the World War. German submarines infested it, and did great damage until a great barrage of mines, laid by American naval vessels, closed it for navigation.
Aiton's Encyclopedia (1910)
a shallow body of water lying between the British Isles and the continent. If the tallest city buildings were set down in the deepest part of the sea, they would rise half way above the surface of the water. The northern boundary may be regarded as a line drawn from the most northerly of the Shetland Isles to the nearest point of the Norwegian coast. The extreme length from north to south is about 700 miles. The distance from Scotland to Denmark is somewhat over 400 miles. The total area of the German Ocean, as it is sometimes called, is somewhat less than 150,000 square miles. Its deepest portion lies off the Norwegian coast. The average depth may be stated at about 175 feet. Numerous arms indent the neighboring coast, the most noted being that formed by the Baltic Sea . Several enormous sandbars or mud banks extend from the mainland. A shallow near the center, known as the Dogger Bank, is famous for its cod fisheries. In fact, the entire sea forms one of the most valuable, if not the most valuable, fishing ground in the world. As a pathway of commerce, the North Sea ranks next to the Mediterranean. The entire basin has been formed by a sinking of the European coast. The British Isles were at one time a part of the mainland.