Deep in a dial-studded cabinet on the Navy's test ship Compass Island lies a hollow sphere of beryllium no bigger than a baseball. It has no visible means of support, yet it spins at 30,000 r.p.m. Awed naval technicians call it a "star in a bottle," and they count on that man-made star to tell nuclear submarines exactly where they are, even after months of cruising in black ocean deeps.
Developed by Minneapolis-Honeywell on theories worked out at the University of Illinois, the bottled star is officially named ESG (Electrically Suspended Gyro). Like all the gyroscopic equipment...