Trenton Sage Jr., age 14, of Hattiesburg, Miss., for his question:

HOW LONG IS EUROPE'S ELBE RIVER?

One of the chief rivers of central Europe is the Elbe River, which flows through Czechoslovakia and Germany. From its headwaters until it ends at the North Sea, the river extends 724 miles with 584 of those miles being navigable, or deep and wide enough for shipping.

In Czechoslovakia the river is called the Labe.

The greatest port in all of Europe, Hamburg, is located on the Elbe River in Germany and is almost 100 miles away from the sea.

For most of its length, the Elbe flows through East Germany. On its banks are Dresden and Meissen, two cities that are noted for their porcelain industry. Also there is Magdeburg, the chemical and industrial center.

The Baltic Sea is connected to the Elbe at Luebeck near Hamburg by a canal deep enough for ocean going ships. Vessels using the canal do not have to make the long trip around Denmark. Barge canals also connect the Elbe with the Rhine to the west and the Oder to the east.