Cartier Tank Cabriolet in Yellow Gold, Circa 1960

Born in the thick of World War I and christened after one of its most terrifying weapons, the Tank is one of Cartier’s earliest wristwatches. Designed by Louis Cartier, this square and rectangular wristwatch was a pioneer in terms of design, in an era still dominated by round pocket watches. But the Tank was a hit, and the collection quickly expanded without deviating too far from the original design, until 1933, when Cartier introduced the Tank Basculante. Its fold-over case makes it one of the most interesting of all Tanks. While the Reverso employs a single track to carry the case from left to right on a horizontal axis, the Cabriolet flips upside down inside a swinging frame; a trick that requires an entirely new solution and case construction, and one that could easily have been over-engineered. Instead, Specialties Horologers SA (later integrated into Jaeger-LeCoultre) designed a simple system, mounting the watch onto a frame secured by a sprung ball bearing, which can be released from the top down. While it isn’t as easy to operate as the Reverso, it offers greater protection to the mechanism. Of course, the additional frame adds eight edges to the design, but this is where the Epicurean taste of Cartier shows. This model is in yellow gold with a white dial, roman numerals, blue steel leaf hands and a brown leather strap, with the crown in gold and blue sapphire on the side.