Edward Lawry Norton

Bell Labs engineer for whom the Norton equivalent circuit is named
(Photograph taken October 13,1925 and reproduced courtesy of the AT&T Archives)

Edward Lawry Norton was born in Rockland, Maine on July 28, 1898. He served as a radio operator in the U.S Navy between 1917 and 1919. He attended the University of Maine for one year before and for one year after his wartime service, then transferred to M.I.T. in 1920, receiving his S.B. degree (electrical engineering) in 1922. He started work in 1922 at the Western Electric Corporation in New York City, which eventually became Bell Laboratories in 1925. While working for Western Electric, he earned a M.A. degree in electrical engineering from Columbia University in 1925. He retired in 1961 and died on January 28, 1983 at the King James Nursing Home in Chatham, New Jersey.

Norton became a Fellow of the Acoustical Society of America and of the IRE (latter in 1961). His 1954 biography, reproduced courtesy of the AT&T Archives, says that he had 19 patents; only 18 of which have been found in U.S. PTO records.

Date Filed
Date Granted
Patent No.
11/24/24 8/21/28 1,681,554 Wave filter  
11/25/24 4/7/31 1,799,634 Wave transmission  
5/12/25 4/16/29 1,708,950 Electric wave filter  
7/18/25 7/2/29 1,719,484 Carrier transmission system  
3/31/26 4/3/28 1,664,755 Electrical network  
9/23/26 9/13/27 1,642,506 Wave transmission system  
10/30/26 10/29/29 1,733,554 Magnetic device  
5/14/27 2/17/31 1,792,497 Vibration clamping device Joint with A.C. Keller
4/16/29 1/13/31 1,788,538 Filtering circuits  
5/31/29 2/17/31 1,792,655 Sound reproducer  
7/29/32 4/17/34 1,954,943 Wave transmission network  
5/19/34 11/5/35 2,019,624 Attenuation equalizer  
8/16/34 4/6/37 2,076,248 Wave filter  
9/30/36 5/3/38 2,115,826 Impedance transformer  
5/12/37 8/16/38 2,126,915 Wave transmission network  
10/18/38 5/21/40 2,201,296 Telephone system Joint with A.A. Lundstrom
9/17/41 7/20/43 2,324,797 Differentiating amplifier  
7/7/47 2/15/55 2,702,186 Accelerometer Joint with G.A. Head

Patents sorted in order of filing date

He published three papers during his lifetime, none of which mention the equivalent circuit associated with him.

Date Title Journal
Pages Comments
April, 1937 Constant resistance networks with applications to filter groups Bell System Technical Journal
Bio on p. 250
June, 1942 Magnetic fluxmeter Bell Laboratories Record
Bio on p. 263
April, 1945 Dynamic measurements on electromagnetic devices Transactions AIEE

His 1942 paper contains two photographs.

Norton wrote 92 technical memoranda (TMs in Bell Laboratories parlance). Because of Norton's lack of publications, it appears that Norton preferred working behind the scenes. As described in the history of Bell Labs, this reticence belied his capabilities.

Norton was something of a legendary figure in network theory work who turned out a prodigious number of designs armed only with a slide rule and his intuition. Many anecdotes survive. On one occasion T.C. Fry called in his network theory group, which included at that time Bode, Darlington and R.L. Dietzold among others, and told them: "You fellows had better not sign up for any graduate courses or other outside work this coming year because you are going to take over the network design that Ed Norton has been doing single-handed." [Taken from p. 210, A History of Engineering and Science in the Bell System: Transmission Technology (1925-1975)]

He applied his deep knowledge of circuit analysis to many fields, and after World War II he worked on Nike missile guidance systems.

On November 11, 1926, he wrote the technical memorandum Design of Finite Networks for Uniform Frequency Characteristic, reproduced courtesy of the AT&T Archives, that contains the following paragraph on page 9.

The illustrative example considered above gives the solution for the ratio of the input to output current, since this seems to be of more practical interest. An electric network usually requires the solution for the case of a constant voltage in series with an output impedance connected to the input of the network. This condition would require the equations of the voltage divided by the current in the load to be treated as above. It is ordinarily easier, however, to make use of a simple theorem which can be easily proved, that the effect of a constant voltage E in series with an impedance Z and the network is the same as a current I=E/Z into a parallel combination of the network and the impedance Z. If, as is usually the case, Z is a pure resistance, the solution of this case reduces to the case treated above for the ratio of the two currents, with the additional complication of a resistance shunted across the input terminals of the network. If Z is not a resistance the method still applies, but here the variation of the input current E/Z must be taken into account.

This paragraph clearly defines what is now known as the Norton equivalent circuit in the United States. Norton never published this result or mentioned it in any of his 18 patents and 3 publications. In Europe, it is known as the Mayer-Norton equivalent. The German telecommunications engineer Hans Ferdinand Mayer published the same result in the same month as Norton's technical memorandum.

Thanks to AT&T Archives for providing much of the information described here.