, Experimenter , Engineer , and Nobel Laureate

The Nobel Foundation was established by the will of Alfred B. Nobel, engineer and chemist, who died in 1895. The will funded annual prizes to “those who shall have conferred the greatest benefit on mankind.” The prize in physics was to go to “the person who shall have made the most important discovery or invention.” In 1912 the Nobel Prize in Physics was awarded to Nils Gustaf Dalén, an engineer, for the invention of an automatic regulating system of valves designed to be used with gas accumulators in lighthouses, lightships, and light buoys. It was the second time the physics prize had been awarded for an invention; the first was to Guglielmo Marconi in 1909 for inventing the wireless telegraph. For many nations, especially Sweden with its long coastline and many islands, the problem of a reliable coastal lighting system had been a pressing one. By 1912 several such nations had installed Dalén systems and had realized both a remarkable improvement in the safety of maritime navigation and an enormous economy in the operation and maintenance of these navigation aids. Nils Gustaf Dalén was born in 1869 at Stenstorp, Sweden, where his family operated a farm. His early education in an agricultural school prepared him to succeed his father as a farmer. His inventive talents became apparent in his work around the farm; in 1892 he invented a device for checking the fat content in milk, and he showed it to Gustaf de Laval, a prominent inventor and industrialist. De Laval’s firm manufactured a new type of reduction gear for high-speed steam turbines that were coming into use in marine applications. (During his lifetime de Laval received more than 90 patents and founded 37 companies.) De Laval recognized Dalén’s abilities and suggested he study engineering at the Chalmers Institute of Technology in Gothenburg. Dalén took this advice and enrolled at Chalmers. In 1896 Dalén graduated as a mechanical engineer with hopes of joining de Laval’s steam turbine company, but de Laval suggested that he continue his studies at the renowned Polytechnische Hochschule in Zurich, Switzerland. Dalén, acting on de Laval’s advice, spent more than a year in Zurich, where he studied under the direction of Prof. Aurel Boleslaw Stodola, who was deeply involved in research on high-pressure water turbines, particularly in the dynamics of their speed regulation devices. It is probable that de Laval, who had studied in Germany, knew Prof. Stodola through their common interest in high-pressure turbines. The relationship between Stodola and his colleague Prof. Adolf Hurwitz in the early 1890s is well known to students of automatic control. It was similar to the relationship between James C. Maxwell and Edward J. Routh in Cambridge some 20 years previously. Maxwell, through his dynamic analysis of the speed governor on a precision electrical measurement device, posed the mathematical problem of determining the conditions on the coefficients of a polynomial that must hold such that the real parts of the roots of the polynomial be negative. Routh determined those conditions and expressed them in an 1876 essay: “A Treatise on the Stability of a Given State of Motion.” In 1893 Stodola, through his work on turbine speed regulators, raised the same question as Maxwell had concerning the relationship between the coefficients of a polynomial and its roots. Unaware of Routh’s solution to that problem, Stodola presented the question to his colleague Hurwitz, and Hurwitz had his solution within a year. It was published in mid-1895. Dalén arrived in Zurich a year after the publication of the Hurwitz paper, and it is likely that as Stodola’s student he became acquainted with the technology of mechanical automatic control devices. After he returned to Sweden in 1897, Dalén continued development work on steam turbines, financed in part by de Laval’s steam turbine company, where their experiments