| 1895 - 1898 | Pupil at the Ècole d'Horlogerie de Besancon and the Ècole des Beaux Art. |
| 1905 | Specialisation in the artistic engraving of clocks and jewellery and cases and mechanisms made from precious metals. He employed twelve people in his workshop. |
| 1911 | Moved to Paris and became a member of the "Circle of Master Engravers" Expansion towards leading jewellery manufacturer in France. Supply of his products worldwide to famous jewellers and clockmakers. |
| 1914 | Manufacture of armament industry, for instance artillery |
| 1919 | Resumption of production of luxury clocks and jewellery. Co-operation with Marius Lavet, a talented engineer who had already been a leading participator in the development of the Bulle clock. The start of the manufacture of the electric clock. |
| 1920 | Start of the production of the electric clock with the name ATO. Earlier, Lavet had worked together with Favre-Bulle on the development of the Bulle clock. Because of his earlier artistic activities, Hatot was able to further develop the ATO clock and research the subject of electric clocks. Edouard Dietsch became the director of his firm. The production of the "ATO Radiola" together with Marius Lavet. The principle of the radio-controlled clock was taken over by the firm of Junghans for their production of the DCF77 in 1980. |
| 1922 | Marius Lavet became the director of des Etablissments Léon Hatot. |
| 1923 | On the 26.09.1923, the Patent number 583331 was applied for in France for the ATO principle. There were 2 basic sizes of the ATO clocks produced. The ½ and ¼ second pendulum. (http://www.germanboran.com/articles/ATO/pendules_ato.jpg) |
| 1924 | ATO produced 4 different models |
| 1925 | In a special research department, a vast varietyof the ATO clock were designed following plans from Leon Hatot. |
| 1926 | 13 different models of the Ato clock were on offer. (http://www.germanboran.com/articles/ATO/ato_anzeige.jpg) รูปจากนสพ. ฝรั่งเศส |
| 1929 | Now over 50 models of the Ato clock were on the market. Delivery to the French railway SNCF of the Ato ½ second pendulum clock, they were highly accepted because of their excellent performance. During the world wide economic slump, Hatot was forced to cooperate with Junghans in Schramberg. The Production and introduction of the first automatic clock called “Rolls”. This patent was sold to Blancpainp |
| 1928 - 1930 | Built under the licence from ATO clocks by the Hamburg American Clock Company HAU. Junghans worked closely with HAU and other clock manu- facturers in a so called interest group. (http://www.germanboran.com/articles/ATO/hau_ato.jpg) (http://www.germanboran.com/articles/ATO/hub_logo.jpg) |
| 1930 | Takeover of HAU by Junghans , leading to worldwide sales of the ATO clocks until about 1962. (http://www.germanboran.com/articles/ATO/junghans_anzeige.jpg) (http://www.germanboran.com/articles/ATO/junghans_logo.jpg) |
| 1938 | Takeover of the firm Paul Garnier. |
| 1939 | Closing of the jewellery branch of the firm. During the war the existing jewellery was stored in a Swiss bank. Not until 1989 were these pieces auctioned in a very remarkable auction and reached extremely high prices. Today these pieces are sought after and are only secretly handled by a few jewelers. |
| 1940 | Closure of the clock production due to the German occupation. Take over of the maintenance of SNCF clock systems. |
| 1949 | Lavet experiments with the deployment of transistor as replacement for the mechanical contact of the ATO clock. |
| 1953 | Lavet and Dietsch get the patent for the transistor controlled pendulum clock with the name ATO. |
| 1967 | Takeover of the electrical clock branch of the firm of Lepaute. Decline in the production of the electrical pendulum clock because of the development of the quartz clock. (http://www.germanboran.com/articles/ATO/grafik02.gif) Firms that produced ATO clocks : Establishment Hatot |