Antoine LeCoultre (1803 – 1881) a self-taught watchmaker set up his workshop in Le Sentier Switzerland in 1833. He worked to hone his craft and in 1844 he invented a new instrument capable of measuring to the micrometre (μm) for the first time. This became the world's most precise measuring instrument called the Millionometer and allowed him to calculate and create the finest components for his watches. LeCoultre exhibited at the 1851 Great Exhibition in London. There Queen Victoria purchased a watch from him and he was awarded a gold medal. Antoine’s son Elie joined the business in 1858 and was instrumental in transforming it. He created a manufacturing workshop whereby all the craftsmen could work under the same roof. When LeCoultre bought all of the craftsman together in 1866 he created the first facility of its kind in the Joux Valley. This allowed all aspects of the watchmaking craft to be executed by LeCoultre in house and allowed his employees to pool their expertise together creating complicated movements. LeCoultre created more than 350 different timepiece calibers, of which 128 were equipped with chronograph functions and 99 with repeater mechanisms all within 30 years. By the end of the century they were making double complication movements, combining both repeaters and chronographs in single pieces. In 1900 Antoine LeCoultre’s grandson Jacques-David took over the business and collaborated with the Parisian-based watchmaker Edmond Jaeger to create ultra-thin movements. During the early 1920s LeCoultre developed the Calibre 101 which was the world’s smallest movement. This helped facilitate the creation of a luxury wrist watch for women which was produced in 1925. Six years later they launched the Reverso. In 1937 the company changed their name to Jaeger-LeCoultre.