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 attended the University of Maine for one year before joining the U.S Navy on April 3, 1917. After being trained in radio operations at various naval facilities and Harvard’s Naval Radio School, he served as an Electrician Second Class Radio (radio operator) on the USS Texan (ID-1354), a cargo ship, from March 25, 1918 to August 30, 1919. He returned to the University of Maine after his wartime service, staying one year before transferring 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, but a twentieth was filed after the date of the biography and granted after he retired.
| Date Filed | Date Granted | Patent No. | Title | Comments |
| 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 | 1,792,497 | Sound Reproducer | |
| 7/29/32 | 4/17/31 | 1,954,943 | Wave Transmission Network | |
| 5/19/34 | 11/5/35 | 2,019,624 | Attenuation Equalizer | |
| 6/9/1934 | 2/16/37 | 2,070,677 | Transmission Network | |
| 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 |
| 8/12/54 | 11/10/64 | 3,156,435 | Command System of Missile Guidance | Joint with J.W. Schaefer |
He published three papers during his lifetime, none of which mention the equivalent circuit associated with him.
| Date | Title | Journal | Volume | Pages | Comments |
| 4/37 | Constant Resistance Networks with Applications to Filter Groups |
Bell System Technical Journal | 16 | 178-193 | Bio p. 250 |
| 6/42 | Magnetic Fluxmeter | Bell Laboratories Record | 20 | 245-247 | Bio p. 263 |
| 4/45 | Dynamic Measurements On Electromagnetic Devices |
Transactions AIEE | 64 | 151-156 |
His 1942 paper contains two photographs.
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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 20 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 for much of the information here.