Science: Electron Fattener

With a flashing of 84 rectifier tubes and a chugging of six great electromagnets, the world's biggest (300 million volt) betatron started operating last week at the University of Illinois. Betatrons look something like cyclotrons, but instead of spinning protons or heavier particles, they spin lightweight electrons.

In the Illinois betatron, the electrons circle a nine-foot, doughnut-shaped tube 140,000 times in four one-thousandths of a second, reach a speed only one-millionth part less than the speed of light. In accordance with Einstein's laws of relativity, the speed increases their mass 600 times. (The last few m.p.h. come hardest. Theoretically, if they...