André Blondel
Encyclopedia
André-Eugène Blondel was a French
engineer and physicist
. He is the inventor of the electromechanical oscillograph
and a system of photometric
units of measurement.
, France. His father was a magistrate from an old family in the town of Dijon
. He was the best student from the town in his year. He went on to attended the École nationale des ponts et chaussées
(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. He became a professor of electrotechnology at the School of Bridges and Highways and the School of Mines
in Paris.
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.
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 and soft iron 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. They paved the way for a greater understanding of the behavior of alternating current
.
Blondel built a theory of rectification
with asymmetrical electrodes. He demonstrated that there were three kinds of electric arc
: the primitive arc of William Duddell
, the secondary arc of Valdemar Poulsen
, 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
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 at Genissiat
on the River Rhone, and transmitted electrical power to Paris more than 350 km away using polyphase AC current
at 120 kV.
He died in Paris on 15 November 1938.
in 1913. He was appointed commander of the Légion d'honneur
in 1927, and was awarded the Faraday Medal
in 1937. He also received the medal of the Franklin Institute
, the Montefiore award and Lord Kelvin award.
In 1942 it was proposed to rename the unit apostilb
the blondel, in his honour.
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
engineer and physicist
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
. He is the inventor of the electromechanical oscillograph
Oscillograph
An oscillograph is an instrument for measuring alternating or varying electric current in terms of current and voltage. There are two instruments that are in common use today:*Electromagnetic oscillograph*Cathode-ray oscilloscope...
and a system of photometric
Photometry (optics)
Photometry is the science of the measurement of light, in terms of its perceived brightness to the human eye. It is distinct from radiometry, which is the science of measurement of radiant energy in terms of absolute power; rather, in photometry, the radiant power at each wavelength is weighted by...
units of measurement.
Life
Blondel was born in Chaumont, Haute-MarneChaumont, Haute-Marne
Chaumont is a commune of France, and the capital of the Haute-Marne department. , it has a of 24,039.The city stands on the Marne River and is situated on the railway linking Paris and Basel, which runs over a 52 m tall and 600 m long viaduct built in 1856.- History :Historically the...
, France. His father was a magistrate from an old family in the town of Dijon
Dijon
Dijon is a city in eastern France, the capital of the Côte-d'Or département and of the Burgundy region.Dijon is the historical capital of the region of Burgundy. Population : 151,576 within the city limits; 250,516 for the greater Dijon area....
. He was the best student from the town in his year. He went on to attended the École nationale des ponts et chaussées
École Nationale des Ponts et Chaussées
Founded in 1747, the École nationale des ponts et chaussées , often referred to as les Ponts, is the world's oldest civil engineering school...
(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. He became a professor of electrotechnology at the School of Bridges and Highways and the School of Mines
École nationale supérieure des mines de Paris
The École Nationale Supérieure des Mines de Paris was created in 1783 by King Louis XVI in order to train intelligent directors of mines. It is one of the most prominent French engineering schoolsThe École Nationale Supérieure des Mines de Paris (also known as Mines ParisTech, École des Mines de...
in Paris.
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.
In 1893 André Blondel sought to solve the problem of integral synchronization, using the theory proposed by Cornu
Marie Alfred Cornu
Marie Alfred Cornu was a French physicist. The French generally refer to him as Alfred Cornu.Cornu was born at Orléans and was educated at the École polytechnique and the École des mines...
. 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 and soft iron oscillographs. These instruments won the grand prize at the St. Louis Exposition
Louisiana Purchase Exposition
The Louisiana Purchase Exposition, informally known as the Saint Louis World's Fair, was an international exposition held in St. Louis, Missouri, United States in 1904.- Background :...
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. They paved the way for a greater understanding of the behavior of alternating current
Alternating current
In alternating current the movement of electric charge periodically reverses direction. In direct current , the flow of electric charge is only in one direction....
.
Blondel built a theory of rectification
Rectification
Rectification has the following technical meanings:* Rectification, in astrology* Rectification , a concept found in biology and industrial chemistry* Chinese history: see Cheng Feng...
with asymmetrical electrodes. He demonstrated that there were three kinds of electric arc
Electric arc
An electric arc is an electrical breakdown of a gas which produces an ongoing plasma discharge, resulting from a current flowing through normally nonconductive media such as air. A synonym is arc discharge. An arc discharge is characterized by a lower voltage than a glow discharge, and relies on...
: the primitive arc of William Duddell
William Duddell
William Du Bois Duddell was a British electro-physicist and electrical engineer. He was privately educated in the UK and France and rose quickly through the prestigious City & Guilds Schools via scholarships...
, the secondary arc of Valdemar Poulsen
Valdemar Poulsen
Valdemar Poulsen was a Danish engineer who developed a magnetic wire recorder in 1899.-Biography:He was born on 23 November 1869 in Copenhagen...
, and a succession of oscillatory discharges.
In 1892, he published a study on the coupling of synchronous generators on a large AC electric grid
Electric power transmission
Electric-power transmission is the bulk transfer of electrical energy, from generating power plants to Electrical substations located near demand centers...
. This analysis had also been done a little earlier by another electrical engineer, Paul Boucherot
Paul Boucherot
Paul Boucherot was an engineer with the Chemin de Fer du Nord . He studied at the elite École supérieure de physique et de chimie industrielles de la ville de Paris where he later also taught electrical engineering...
, using a different approach, and the two authors arrived at similar conclusions.
In 1894 he proposed the lumen
Lumen (unit)
The lumen is the SI derived unit of luminous flux, a measure of the total "amount" of visible light emitted by a source. Luminous flux differs from power in that luminous flux measurements reflect the varying sensitivity of the human eye to different wavelengths of light, while radiant flux...
and other new measurement units for use in photometry, based on the metre and the Violle candle
Jules Violle
Jules Louis Gabriel Violle was a French physicist and inventor.He is notable for having determined the solar constant at Mont Blanc in 1875, and, in 1881, for proposing a standard for luminous intensity, called the Violle, equal to the light emitted by 1 cm² of platinum at its melting point...
. He coined the names of the phot
Phot
A phot 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...
and the stilb
Stilb (unit)
The stilb is the CGS unit of luminance for objects that are not self-luminous. It is equal to one candela per square centimeter or 104 nits . The name was coined by the French physicist André Blondel around 1920. It comes from the Greek word stilbein meaning "to glitter".It was in common use in...
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 at Genissiat
Injoux-Génissiat
Injoux-Génissiat is a commune in the Ain department in eastern France.-Population:-References:*...
on the River Rhone, and transmitted electrical power to Paris more than 350 km away using polyphase AC current
Polyphase system
A polyphase system is a means of distributing alternating current electrical power. Polyphase systems have three or more energized electrical conductors carrying alternating currents with a definite time offset between the voltage waves in each conductor. Polyphase systems are particularly useful...
at 120 kV.
He died in Paris on 15 November 1938.
Honours and awards
Blondel was made a life member of the French Academy of SciencesFrench Academy of Sciences
The French Academy of Sciences is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research...
in 1913. He was appointed commander of the Légion d'honneur
Légion d'honneur
The Legion of Honour, or in full the National Order of the Legion of Honour is a French order established by Napoleon Bonaparte, First Consul of the Consulat which succeeded to the First Republic, on 19 May 1802...
in 1927, and was awarded the Faraday Medal
Faraday Medal
The Faraday Medal is a medal awarded by the Institution of Electrical Engineers The bronze medal is awarded without restriction as regards nationality, country of...
in 1937. He also received the medal of the Franklin Institute
Franklin Institute
The Franklin Institute is a museum in Philadelphia, Pennsylvania, and one of the oldest centers of science education and development in the United States, dating to 1824. The Institute also houses the Benjamin Franklin National Memorial.-History:On February 5, 1824, Samuel Vaughn Merrick and...
, the Montefiore award and Lord Kelvin award.
In 1942 it was proposed to rename the unit apostilb
Apostilb
The apostilb is an old unit of luminance, which was withdrawn from use in 1978. The SI unit of luminance is the candela per square metre . In 1942 it was proposed to rename the apostilb the blondel, after the French physicist André Blondel...
the blondel, in his honour.