The Nobel Prize in Physics 1912
Nils Gustaf Dalén
Born: 30 November 1869, Stenstorp, Sweden
Died: 9 December 1937, Stockholm, Sweden
Affiliation at the time of the award: Swedish Gas-Accumulator Co., Lidingö-Stockholm, Sweden
Prize motivation: "for his invention of automatic regulators for use in conjunction with gas accumulators for illuminating lighthouses and buoys"
Field: applied mechanics, mechanics
For centuries, lighthouses have made navigation safer. During the 19th century, acetylene became the standard light source. Gustaf Dalén developed a method to flash the light in short frequencies thereby reducing gas consumption. In 1907, he invented a regulating valve based on the difference in expansion for black and white metal rods. The "solar valve" made it possible to extinguish the light during day-time.