1910 Observatoire Central de l'Indochine Map of the China Sea to Track Typhoons

This is a c. 1910 ferro-gallic printed Observatoire Central de l'Indochine typhoon tracking map of Vietnam and the South China Sea - a wonder of early infographic weather mapping and data transmission. The map is an innovative guide to transmitting typhoon data gathered by remote weather monitoring stations with the central observatory at Phu Liên (northern Vietnam) via the Semaphore System or Optical Telegraph.

The Semaphore Telegraph

The semaphore is an optical telegraph invented by the French engineer Claude Chappe (1763 - 1805) during the Napoleonic Era (1799 - 1815). It consisted of a network of line-of-sight towers with mechanized lighting systems that could communicate complex data through pre-determined light and color patterns. Semaphores fell out of fashion in Europe by the mid-19th century, when electric telegraph lines were broadly implemented. However, in distant colonies, where wired telegraph systems were slow to emerge or difficult to manage, or in instances where communication with off-shore ships and light stations was essential, they remained in use until the early 20th century. The semaphore model was also adopted for aeronautical and maritime use.

The introduction of a semaphore system at Phu Liên was an innovative approach to resolving communication issues between the central observatory and far-flung weather stations. While French Indochina had a sophisticated wired telegraph system, it did not extend to remote monitoring stations that regularly reported storm data to the Phu Liên. Instead, the observatory resorted to the semaphore system of a century earlier to quickly and effectively transmit critical in-the-moment typhoon data. At Phu Liên, the data was compiled before wired telegraphs communicated storm warnings throughout French Indochina and to neighboring countries.

Above and below the map, the adapted and revised 'semaphore code' (code semaphorique) is explained. Bullet points detail how the code can communicate information concerning typhoons. Data that could be transmitted includes wind direction, the relative position of the typhoon, storm speed (even if it's an estimate), and more. Another table provides notes on interpreting the light signals at night.

A Closer Look

The map is intended to track and transmit typhoon data by a novel adaptation of the semaphore optical telegraph system. Using this map, a semaphore operator could communicate, storm type, directions, wind speeds, longitude, and latitude. Centered on Luzon, the Philippines, coverage embraces from Shanghai south to the Malay Peninsula and Northern Borneo and from Thailand east to the Pacific Ocean, including the Philippines, Vietnam, Taiwan, and southeastern China. Major cities and loose political boundaries are identified, and the whole is set on a longitude and latitude grid graduated by degree. Instructions on using the 'Semaphore Code' appear above and below the map.

The Observatoire Central de l'Indochine

The Observatoire de l'Indochine, also known as the Observatory at Phu Liên, was established in 1902 by the French colonial administration to study weather in Indochina. Situated just south of Haiphong, the observatory tracked and disseminated storm information throughout French Indochina. It remained active until World War II (1939 - 1945), providing advance warning of some 400 typhoons, many of which made landfall. Today Phu Liên is a popular tourist destination known as the Tonkin or Haiphong Observatory.

Ferro-Gallic Print

Ferro-Gallic printing, also called 'Iron Gall Print' is a photo-reproductive process developed in 1859 by Alphonse Louis Poitevin. The process became popular in the late 1880s when it was introduced commercially, particularly as it could be used to make fast copies of tracings and allowed for corrections to be made during the printing process. Moreover, copies could be made directly from originals without an intermediary negative process. Due to the chemicals used in this process, the background is never white, instead taking on a pale brown to lavender tint. Like most photo-reproductive processes of the period, ferro-gallic printing was useful only for short-run printing, usually of less than five copies, and impractical for mass production. Moreover, due to the photoreactive nature of the print, and the low-quality field papers generally used, ferro-gallic prints rarely survive more than 30 years or so, making the early examples extremely scarce. The ferro-gallic process is similar to the Diazo Print or Whiteprint process, which replaced it in popularity in the early 20th century.

Publication History and Census

While this map does not bear publication information, it is certain to have been printed by the Observatoire Central de l'Indochine in the first decade of the 20th century, likely between 1905 and 1910. The ferro-gallic process limited the number of impressions to about five copies, so it is extremely rare, this being the only known surviving example.