In 1976, Briatore and Leschiutta compared the rates of two cesium clocks, one in Turin 250 m (820 ft) above sea level, the other at Plateau Rosa 3,500 m (11,500 ft) above sea level. The comparison was conducted by evaluating the arrival times of VHF television synchronization pulses and of a LORAN-C chain. The predicted difference was 30.6 ns/d.