Wayne Leiss, age 10, of Newport News, Va., for his question:

Who invented the tape recorder?

This copycat gadget does its work with the help of millions of small particles of magnetic iron. It records sounds on a roll of tape. The tape is played back to repeat the record. The principles upon which the instrument is based were discovered by the scientist Vlademar Poulsen near the end of the last century.

Poulsen the scientist then became Poulsen the inventor, and he put his principles to work. He created the world's first tape recorder and exhibited it at the Paris exposition in 1900. The tape recorder attracted world wide attention, and a prize was awarded to its inventor, Vlademar PoulSen.