Its calibre 478BWSbr movement is derived from military watches and incorporates the best watchmaking technology of that time:

• a stop second for precise timesetting, a glucydur balance for stability through changes in temperature and fitted with a shock absorber;
• a "swan neck" index for micrometric adjustment; and the essential soft-iron inner case that protects this exceptional mechanism from the effects of magnetism.

The Jaeger-LeCoultre Geophysic®Chronomètre watch was created in 1958, the International Geophysical Year, and has served as the quintessential symbol of precision and reliability with a design of undeniable purity.

Since this exceptional instrument had been designed to withstand magnetic fields of up to 600 gauss and to maintain its prodigious precision in all circumstances, the Jaeger-LeCoultre Geophysic®Chronomètre watch was the perfect present for the first man to have headed an expedition beneath the North Pole.

In 2014, Jaeger-LeCoultre pays tribute to this legendary creation by unveiling The Geophysic® 1958, three exclusive watches featuring a slightly larger diameter of 38.5 mm to meet the comfort requirements of the 21st century. One model in steel, another in pink gold and the third in platinum, all are equipped with the Jaeger-LeCoultre Calibre 898/1, considered one of the most precise and reliable in-house automatic movements on the market today.