Dalén, Nils Gustaf

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Nils Gustaf Dalén

Swedish inventor Nils Gustaf Dalén (1869–1937) revolutionized maritime navigation and became known as "the benefactor of sailors" for his contributions to lighthouse technology. Dalén's inventions centered on the containment, storage and long–term use of acetylene gas, as well as on automation and differentiation of light sources. His work enabled lighthouses to operate more effectively and to be placed in remote areas. He received the Nobel Prize in Physics in 1912 for his work.

Dalén was born on November 30, 1896, on the Skrä ddargåden farm in Stenstorp in the Västergötland province of Sweden. He was the fourth of five children born to Anders Johannson, a farmer, and his wife Lovisa Andersdotter Dalén. All of the children adopted their mother's maiden name. Although the children were expected to take over the family farm, Lovisa also stressed the importance of education. Dalén demonstrated an early talent for invention. As a child, he became known throughout his district for devising a "bed roller" that made coffee and switched on the light. He also developed an automatic threshing machine powered by an old spinning wheel.

Turned To Engineering

Dalén eventually enrolled in an agricultural school to study dairy farming. While in school, he worked on the family farm and also started a market garden and opened both a seed store and a dairy. In 1892, he invented a milk–fat tester to measure the quality of the milk he sold. He presented his invention to the prominent Swedish inventor Gustaf de Laval, who suggested he pursue a career in engineering. Dalén sold the farm and, at the age of 23, he enrolled in the Chalmer's Institute of Technology in Göteborg. Following his graduation from the Institute in 1896, Dalén spent a year in Zurich, Switzerland, studying at the prestigious Swiss Federal Institute of Technology.

Upon his return to Sweden, Dalén worked briefly for the de Laval Steam Turbine Company in Stockholm, where he helped develop hot air turbines, compressors, and air pumps. In 1900, he and Henrik Celsning, a classmate, formed the firm Dalén and Celsing to devise and market their own inventions. Among the pair's projects was the creation of the Brilliant gasworks, which they sold to the town of Ängelholm. The following year Dalén became technical chief of Swedish Carbide and Acetylene and he subsequently joined the Gas Accumulator Company, where he was named chief engineer in 1906. On July 13, 1901, Dalén married his childhood sweetheart, Elma Axelia Persson. The couple had two sons and two daughters.

Improved Lighthouse Technology

Dalén joined the Gas Accumulator Company at a time when maritime communication needs were growing. Lighthouses and light buoys at the time were powered by petroleum gas, which provided only low–wattage illumination. Furthermore, the technology required constant personal inspection. The need for an improved, automated system was especially great in Sweden, with its long coastline and large collection of archipelagos, where light sources were needed but could not be regularly accessed and maintained. In 1895, scientists devised a method for large–scale preparation of the gaseous hydrocarbon acetylene from calcium carbide. This discovery was significant to the lighthouse industry because acetylene produces a strong, white light. The petroleum used in lighthouses at the time was compressed and enclosed in large iron containers. Acetylene, it was discovered, became highly explosive under pressure and, thus, could not be treated the same way. Another attempted method involved the storage of calcium carbide in light buoys, allowing acetylene to escape under automatically supplied water pressure. This setup proved unwieldy, unreliable and unworkable in cold weather, however.

In 1896, two French chemists discovered that acetylene, when dissolved in acetone, produces a non–explosive solution. Acetylene could not be stored this way, however, because even in a pressurized container filled to the brim, explosive acetylene gas would be produced in the space above the liquid's surface upon consumption or cooling. The discovery was then made that acetylene would remain non–explosive if compressed in a porous mass. Numerous unsuccessful attempts were made to devise such a substance. The Gas Accumulator Company had purchased the patent rights to dissolved acetylene in 1901 and Dalén began working to solve this problem. He became the first to devise a workable solution. In Dalén's process, a porous acetylene mass was enclosed in a steel container which was then half–filled with acetone and compressed at a pressure of ten atmospheres and a temperature of 15 degrees Celsius. These conditions produced non–explosive acetylene at 100 times the volume of the container, creating a ready supply of what became known as aga, to be used in a lighthouse or lightbuoy. The invention was also used in early traffic signals, on public transit systems and in aviation lighting equipment.

Made Further Discoveries

While Dalén's discovery was significant, additional challenges remained. Light sources could not burn aga without interruption due to the high cost and the fact that steady signals would not permit distinction between lighthouses. At the time, signals from some petroleum–based lights were differentiated using moving screens or rotating lighting devices, but both these methods were expensive. In most lighthouses, devices designed to eclipse the light or create flashing were powered by the escaping petroleum. The flashes lasted five to seven seconds, but such length was unnecessary with the much brighter acetylene lamps. Dalén began to seek solutions to this problem in 1904, eventually devising an apparatus that, through instantaneous opening and closing of a gas pipe, enabled one liter of acetylene gas to produce several thousand rapid yet distinct flashes of light. The apparatus also allowed each light source to adopt a specific, Morse Code–like pattern. Dalén devised a supplementary apparatus as well—a burner that could be fitted with a small permanent flame that would light a 3/10–second flash every three seconds.

In 1907, Dalén further refined his invention when he developed a "solar valve" that extinguished the light at sunrise and reignited it under cloud cover or fog and at nightfall. The valve was controlled by four metal rods, one black and three highly polished, inside a glass tube. The dark rod absorbed light during the daytime, causing it to heat and expand, closing the gas valve. As daylight waned, the dark rod cooled to the temperature of the other rods, contracting and allowing the valve to reopen. This apparatus, combined with Dalén's intermittent light, resulted in a gas savings of 93 percent over the earlier technology. The cost–effective and automated nature of Dalén's inventions also resulted in significantly increased use of light sources for maritime navigation. "The use of aga light facilitates the placing of lighthouses and lightbuoys in the most inaccessible places such as archipelagos and seas with dangerous reefs," observed H.G. Söderbaum, President of the Royal Swedish Academy of Sciences, in his 1912 Nobel Prize presentation speech. "With the use of one or more of the easily transportable gas accumulators, such lights can give their warning or guiding signals for a whole year or more without the need of inspection or the fear of failure."

Lost Eyesight, Won Nobel

In 1909 the Gas Accumulator Company was reorganized under the name Swedish Gas Accumulator, commonly called AGA, and Dalén was appointed managing director. In 1911, the company filled a lucrative $150,000 order to create a lighting system for the Panama Canal. Dalén continued to work on new inventions, as well as refining his earlier discoveries, resulting in a tragic accident in 1912. While testing safety devices on acetylene cylinders, a sudden explosion injured him severely and caused him to lose his eyesight. Dalén recovered from his injuries but remained permanently blind. That same year, he was awarded the Nobel Prize in Physics. His brother Albin, a professor and ophthalmologist at the Caroline Institute, accepted the award on his behalf, as Dalén was still bedridden at the time. In his presentation speech, Söderbaum noted the far–reaching effects of Dalén's work. "Most of the maritime nations have now started to install these Dalén devices, and they are found operating from Spitzberg, the Varanger Fjord, Iceland and Alaska in the north, to the Straits of Magellan and Kerguelen Island in the south. The annual benefit to navigation can be expressed in terms of saving of thousands of human lives and of hundred of millions of Kronor." Dalén used the prize money to provide every AGA employee with an extra week's wages and to establish a scholarship fund at the Chalmers Institute.

He returned to AGA in February 1913 and remained at the company's helm until his death in 1937. Despite the loss of his eyesight, Dalén continued to pursue new inventions, including a coke–fueled, low–energy oven that could burn for 24 hours. He also became involved in civic life, sitting on the city council of the town of Lindingö for almost 20 years. During a Swedish financial crash in 1932, Dalén distributed lapel pins bearing the motto "Be Optimistic," and he took his own advice, as expressed in his New York Times obituary in 1937. "I have much to be thankful for," he was quoted as having once said. "Here I have my phones, linking me with my business associates and friends. Necessity has taught me how to conduct my researches without my eyes. There is always someone at home to read to me, and after that I have my radio. The theater is one of my favorite recreations."

Dalén received many honors in addition to the Nobel Prize. He was named a member of the Royal Swedish Academy of Sciences in 1913 and the Swedish Academy of Science and Engineering in 1919. The International Acetylene Association awarded him its Morehead Medal in 1933. He died of cancer at his home in Lidingö on December 9, 1937. His eldest son, Gunnar, succeeded him as president of AGA. In 1996, AGA president and CEO Marcus Storch inaugurated the Dalén Museum in Stenstorp, dedicated to the inventor's life and work.


Nobel Lectures. Physics 1901–1921, Elsevier Publishing Company, 1967.

Notable Scientists: From 1900 to the Present, Gale Group, 2001.


"Gustaf Dalén," AGA website,http://www.aga.com (November 29, 2004).