André-Eugène Blondel (28 August 1863 – 15 November 1938) was a French engineer and

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate caus ...

. He is the inventor of the electromechanical

oscillograph An oscilloscope (informally a scope) is a type of electronic test instrument that graphically displays varying electrical voltages as a two-dimensional plot of one or more signals as a function of time. The main purposes are to display repetiti ...

and a system of photometric units of measurement.

Life

Blondel was born in

Chaumont, Haute-Marne Chaumont () is a Communes of France, commune of France, and the capital (or ''préfecture'') of the Haute-Marne department. , it has a population of 21,847. The city stands on the river Marne (river), Marne and is situated on the Paris-Est–Mu ...

, France. His father was a magistrate from an old family in the town of

Dijon Dijon (, , ) (dated) * it, Digione * la, Diviō or * lmo, Digion is the prefecture of the Côte-d'Or department and of the Bourgogne-Franche-Comté region in northeastern France. the commune had a population of 156,920. The earlies ...

. He was the best student from the town in his year. He went on to attend the

École nationale des ponts et chaussées École may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * École, Savoi ...

(School of Bridges and Roadways) and graduated first in his class in 1888. He was employed as an engineer by the Lighthouses and Beacons Service until he retired in 1927 as its general first class inspector.See IEEE Industry Applications Magazine May–June 2004 He became a professor of electrotechnology at the School of Bridges and Highways and the

School of Mines A school of mines (or mining school) is an engineering school, often established in the 18th and 19th centuries, that originally focused on mining engineering and applied science. Most have been integrated within larger constructs such as minera ...

in Paris.See Hebrew University of Jerusalem Very early in his career he suffered immobility due to a paralysis of his legs, which confined him to his room for 27 years, but he never stopped working.See Academie de Poitiers In 1893 André Blondel sought to solve the problem of integral synchronization, using the theory proposed by Cornu. He determined the conditions under which the curve traced by a high-speed recording instrument would follow as closely as possible the actual variations of the physical phenomenon being studied. This led him to invent the

bifilar A bifilar coil is an electromagnetic coil that contains two closely spaced, parallel windings. In engineering, the word ''bifilar'' describes wire which is made of two filaments or strands. It is commonly used to denote special types of winding ...

and

soft iron A magnetic core is a piece of magnetic material with a high magnetic permeability used to confine and guide magnetic fields in electrical, electromechanical and magnetic devices such as electromagnets, transformers, electric motors, generators, in ...

oscillographs. These instruments won the grand prize at the St. Louis Exposition in 1904. They were more powerful than the classical stroboscope, invented in 1891 then in use. They remained the best way to record high-speed electrical phenomena for more than 40 years when they were replaced by the

cathode ray oscilloscope An oscilloscope (informally a scope) is a type of electronic test instrument that graphically displays varying electrical voltages as a two-dimensional plot of one or more signals as a function of time. The main purposes are to display repetiti ...

. They paved the way for a greater understanding of the behavior of

alternating current Alternating current (AC) is an electric current which periodically reverses direction and changes its magnitude continuously with time in contrast to direct current (DC) which flows only in one direction. Alternating current is the form in whic ...

. Blondel built a theory of rectification with asymmetrical electrodes. He demonstrated that there were three kinds of

electric arc An electric arc, or arc discharge, is an electrical breakdown of a gas that produces a prolonged electrical discharge. The electric current, current through a normally Electrical conductance, nonconductive medium such as air produces a plasma (p ...

: the primitive arc of

William Duddell William Du Bois Duddell (1 July 1872, in Kensington, London – 4 November 1917, in Wandsworth, London) was an English physicist and electrical engineer. His inventions include the moving coil oscillograph, as well as the thermo-ammeter and t ...

, the secondary arc of

Valdemar Poulsen Valdemar Poulsen (23 November 1869 – 23 July 1942) was a Danish engineer who made significant contributions to early radio technology. He developed a magnetic wire recorder called the telegraphone in 1898 and the first continuous wave radio ...

, and a succession of oscillatory discharges. In 1892, he published a study on the coupling of synchronous generators on a large AC electric grid. This analysis had also been done a little earlier by another electrical engineer, Paul Boucherot, using a different approach, and the two authors arrived at similar conclusions. In 1894 he proposed the lumen and other new measurement units for use in photometry, based on the metre and the Violle candle. He coined the names of the

phot A phot (ph) is a photometric unit of illuminance, or luminous flux through an area. It is not an SI unit but rather is associated with the older centimetre–gram–second system of units. The name was coined by André Blondel in 1921.Parry Moo ...

and the stilb around 1920. In 1899, he published ''Empirical Theory of Synchronous Generators'' which contained the basic theory of the two armature reactions (direct and transverse). It was used extensively to explain the properties of salient-pole AC machines. In 1909, assisted by M. Mähl, he worked on one of the first long distance schemes for the transmission of AC power. The project created a (then) large 300,000 hp

hydroelectric power plant Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and ...

at Genissiat on the

Rhône The Rhône ( , ; wae, Rotten ; frp, Rôno ; oc, Ròse ) is a major river in France and Switzerland, rising in the Alps and flowing west and south through Lake Geneva and southeastern France before discharging into the Mediterranean Sea. At Ar ...

, and transmitted electrical power to Paris more than 350 km away using polyphase AC current at 120 kV. In 1914 he performed a series of experiments in order to determine what was the most general law of

electromagnetic induction Electromagnetic or magnetic induction is the production of an electromotive force (emf) across an electrical conductor in a changing magnetic field. Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk ...

. He died in Paris on 15 November 1938.

Honours and awards

Blondel was made a member of the

French Academy of Sciences The French Academy of Sciences (French: ''Académie des sciences'') is a learned society, founded in 1666 by Louis XIV of France, Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French Scientific me ...

in 1913. He was appointed commander of the

Légion d'honneur The National Order of the Legion of Honour (french: Ordre national de la Légion d'honneur), formerly the Royal Order of the Legion of Honour ('), is the highest French order of merit, both military and civil. Established in 1802 by Napoleon ...

in 1927, and was awarded the

Faraday Medal The Faraday Medal is a top international medal awarded by the UK Institution of Engineering and Technology (IET) (previously called the Institution of Electrical Engineers (IEE)). It is part of the IET Achievement Medals collection of awards. T ...

in 1937. He also received the medal of the

Franklin Institute The Franklin Institute is a science museum and the center of science education and research in Philadelphia, Pennsylvania. It is named after the American scientist and statesman Benjamin Franklin. It houses the Benjamin Franklin National Memori ...

, the Montefiore award and Lord Kelvin award. In 1942 Parry Moon proposed to rename the unit of

luminance Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted from, or is reflected from a particular area, and falls withi ...

apostilb The apostilb is an obsolete unit of luminance. The SI unit of luminance is the candela per square metre (cd/m2). In 1942 Parry Moon proposed to rename the apostilb the blondel, after the French physicist André Blondel. The symbol for the apostilb i ...

the ''blondel''.

Notes

References

André Blondel - French Scientist and Engineer
by Gerard-Andre Capolino in IEEE Industry Applications Magazine, May/June 2004. Accessed June 2008

Institute of Chemistry at The Hebrew University of Jerusalem. Published on April 17, 2003. Accessed June 2008
Some portraits - Andre Blondel
Academie de Poitiers, France. Accessed June 2008 (French) {{DEFAULTSORT:Blondel, Andre-Eugene French civil engineers École Polytechnique alumni École des Ponts ParisTech alumni Corps des ponts 1863 births 1938 deaths Commandeurs of the Légion d'honneur French physicists Members of the French Academy of Sciences Honorary Members of the USSR Academy of Sciences 19th-century French inventors

Life

Honours and awards

See also

Notes

References