Milestone-Proposal talk:Anderson Bridge

Advocates’ Checklist

1. Is proposal for an achievement rather than for a person? If the citation includes a person's name, have the proposers provided the required justification for inclusion of the person's name?
2. Was proposed achievement a significant advance rather than an incremental improvement to an existing technology?
3. Were there prior or contemporary achievements of a similar nature?
4. Has the achievement truly led to a functioning, useful, or marketable technology?
5. Is proposal adequately supported by significant references (minimum of five) such as patents, contemporary newspaper articles, journal articles, or citations to pages in scholarly books? At least one of the references from a peer-reviewed scholarly book or journal article. The full text of the material, not just the references, shall be present. If the supporting texts are copyright-encumbered and cannot be posted on the ETHW for intellectual property reasons, the proposers shall email a copy to the History Center so that it can be forwarded to the advocate. If the advocate does not consider the supporting references sufficient, the advocate may ask the proposer(s) for additional ones.
6. Are the scholarly references sufficiently recent?
7. Is proposed citation readable and understandable by the general public?
8. Does the proposed plaque site fulfill the requirements?
9. Is the proposal quality comparable to that of IEEE publications?
10. Scientific and technical units correct? (e.g. km, mm, hertz, etc.) Are acronyms correct and properly upperercased or lowercased?
11. Date formats correct as specified in Section 6 of Milestones Program Guidelines? https://ieeemilestones.ethw.org/Helpful_Hints_on_Citations,_Plaque_Locations

Reviewers’ Checklist

1. Is suggested wording of the Plaque Citation accurate?
2. Is evidence presented in the proposal of sufficient substance and accuracy to support the Plaque Citation?
3. Does proposed milestone represent a significant technical achievement?
4. Were there similar or competing achievements? If so, have the proposers adequately described these and their relationship to the achievement being proposed?

In answering the questions above, the History Committee asks that reviewers apply a similar level of rigor to that used to peer-review an article, or evaluate a research proposal. Some elaboration is desirable. Of course the Committee would welcome any additional observations that you may have regarding this proposal.

Submission and Approval Log

Submitted date: 14 March 2023
History Committee approval date: 11 June 2024
Board of Directors approval date: 27 September 2024

1. Were there similar or competing achievements? If so, have the proposers adequately described these and their relationship to the achievement being proposed?

Original Title and Citation as submitted. Uploaded by -- Administrator4 (talk) 15:34, 14 March 2023 (UTC)

Anderson Bridge 1891

The Anderson Bridge measures inductance in an ac bridge. The unknown inductance is compared with a standard fixed capacitance, which is connected between two arms of the bridge. It works in a similarly to the Wheatstone Bridge, used to measure resistance. Anderson's method is capable of precise measurements of inductance over a wide range of values from a few micro-Henrys to several Henrys

Advocate's address to the proposers -- Savini (talk) 16:39, 25 February 2024 (UTC) -- Savini (talk) 16:39, 25 February 2024 (UTC)

I have just been appointed as the advocate of your proposal. It will be a pleasure for me to work with you in processing the application

The names of IEEE technical Societies that may be interested in the subject of the application: Instrumentation and Measurements Society Magnetics Society Power Electronics Society

200.-250 words abstract:

In the mid 19th century, as the field of electrical engineering was evolving, there was great interest in the measurement of electrical components viz. resistance, inductance and capacitance. Michael Faraday and Joseph Henry independently discovered inductance in 1831/32. James Clerk Maxwell introduced a ballistic deflection method for measuring inductance in 1865. This was a variation on the Wheatstone Bridge (1843) for measuring resistance. The first bridge to measure inductance was the Maxwell Bridge based on the principle of balancing the L/R time constant of the inductor against a known RC time constant of a capacitor. Several modifications followed and the most famous one was the Anderson Bridge (1891) named after Alexander Anderson, Professor of Natural History at the Queen’s College, Galway, now known as the University of Galway. The Maxwell Bridge, was based on the deflection of a ballistic galvanometer, which was difficult to calibrate due to its dependance on a moving coil to detect small movements near the balance points. The Anderson Bridge removed this obstacle by balancing the L/R time constant of an unknown inductor with the stable RC time constant of a capacitor. The Anderson Bridge became the de facto bridge for measuring inductance, as described in the U.S. Bulletin on the Bureau of Standards. The Anderson Bridge remained the standard bridge for measuring inductance until the advent of digital methods in the 1970’s. Most undergraduate textbooks up until that time referenced the Anderson Bridge for the measurement of inductance.

Antonio Savini

Expert Reviews -- Savini (talk) 18:25, 21 May 2024 (UTC)

As the Advocate of the Milestone proposal, here below I upload the reviews I have received from the two experts who have assessed the proposal. At the same time I invite the proposer to consider the experts' reviews carefully and then to improve the proposal and the citation accordingly, and finally to upload the result. Thanks

Antonio Savini

Re: Expert Reviews -- Wghurley (talk) 10:57, 22 May 2024 (UTC)

Replace this text with your reply

I have consulted with the PELS History Committee and with the UKRI Life Members Committee and propose the following citation

The Anderson Bridge developed here is an ac bridge specialised for the measurement of electrical inductance. The unknown inductance value is compared with the capacitance of a fixed reference capacitor. It is a modified version of the Maxwell Bridge. It works in a manner similar to the Wheatstone Bridge, used to measure resistance. Anderson's bridge is capable of precise measurements of inductance ranging from a few microhenries to several henries Word Count: 70

Re: Re: Expert Reviews -- Savini (talk) 15:40, 27 May 2024 (UTC)

Replace this text with your reply

The proposer is invited to make a further cleaning of the citation text. In fact, in the proposed text different ways are used to identify the same thing i.e: " Anderson Bridge", "Anderson's Bridge", "Anderson bridge". I suggest to use "Anderson Bridge" everywhere, which, by the way, avoids the special character "'".

Antonio Savini

Comments re: Spelling, Inconsistencies, etc. -- Bberg (talk) 23:25, 31 May 2024 (UTC)

I hereby provide some comments about this proposal.

First, a comment above incorrectly cites some of the names of societies within whose fields of interest the Milestone proposal resides. The proposer should add these 3 societies into the field for the technical societies and technical councils in the proposal, and the following wording should be used: "Instrumentation and Measurement Society (IMS), Magnetics Society, and Power Electronics Society (PELS)"

Second, the above Abstract as proposed by Advocate Antonio Savini should be inserted into the Abstract section of the proposal.

Third, as the IEEE Authoritative Dictionary of IEEE Standards Terms ("IEEE Dictionary") does not include an apostrophe in the name "Anderson Bridge," this should be the manner in which this name appears throughout the proposal. This is not a current problem, but I note this since its logic is different from what Antonio Savini noted above.

Fourth, based on what was set forth at the August 1893 International Congress of Electricians, the unit of inductance as named after Joseph Henry is spelled "henry" (not capitalized), and thus microhenry is also proper. Plural forms retain the "y" so as to adhere to the original name, as in henrys and microhenrys.

Fifth, since we are reciting the last name of the gentleman responsible, we should certainly include his first name in the citation, as in "Alexander Anderson."

Sixth, the proposal itself does not include the required Justification section re: the inclusion of Alexander Anderson's name in the citation. I propose the following for this.

Alexander Anderson is indisputably the originator of what came to be known at the Anderson Bridge. His 1891 paper is Reference 1, and its first page can be seen at https://www.tandfonline.com/doi/abs/10.1080/14786449108620116. This came to be known at "Anderson's Method" in the paper at Reference 2, fully available at https://nvlpubs.nist.gov/nistpubs/bulletin/01/nbsbulletinv1n3p291_A2b.pdf. Anderson's 1891 paper cites this as "Anderson's Bridge" in Reference 4 on p. 8, fully available at https://www.ietlabs.com/pdf/GenRad_History/A_History_of_Z_Measurement.pdf. There appears to be no doubt about its originator being Alexander Anderson, and indeed the IEEE Dictionary calls it the "Anderson Bridge." Thus, it certainly is necessary to include this gentleman's full name in the citation.

Seventh, the PELS proposed citation as shown earlier in these Comments is much improved over what is currently on the main page, and it addresses all of my comments above with two exceptions: (1) it does not include Anderson's first name, (2) it uses "ac" instead of "AC" (and I would argue that AC reads better in the citation, particularly when read by a layperson), and (3) it uses "ies" instead of "ys" in the pluralized form of henry. I hereby propose the following citation based on the PELS version with these changes. I note that it reads a bit more efficiently at 69 words (down from 70), and I feel that it also reads a bit more smoothly:

The Anderson Bridge developed here is an AC bridge specialised for measuring electrical inductance wherein the unknown inductance value is compared with the capacitance of a fixed reference capacitor. As a modified version of the Maxwell Bridge, it operates in a manner similar to how the Wheatstone Bridge measures resistance. Alexander Anderson's invention is thereby capable of precise measurements of inductance ranging from a few microhenrys to several henrys.

Re: Comments re: Spelling, Inconsistencies, etc. -- Bberg (talk) 15:56, 1 June 2024 (UTC)

In separate email communications with proposer Gerard Hurley, my proposals above were all accepted. Here are some additional comments and requests.

Add a comma before "1891" in the title of the Milestone.

Add this new paragraph to the "historical significance" section, preceded by a blank line:
At the August 1893 International Congress of Electricians, the unit of inductance was standardised as “henry” in honor of Joseph Henry.[8] As such, the unit "microhenry" is also proper. While these two plural forms are both used widely ("henrys" and "henries"), the former is used in the citation to best honor the name of Joseph Henry.

Add this as Reference 8 as used just above: https://siarchives.si.edu/collections/siris_sic_12595

Following the above addition to the "historical significance" section, add my "Justification" statement (the "sixth" point above), preceded by a blank line and a boldface header reading "Justification for inclusion of the name of Alexander Anderson in the Citation".

Citation comments: While the word "here" is understood to be the University of Galway when the physical plaque is read, including the university's name in the citation itself would be optimal so that the wording can be separately recited and best appreciated. As such, I propose that the last sentence be trimmed a bit, and the first sentence appropriately altered, resulting in one additional word and reaching the maximum of 70 words, as follows:

Developed at the University of Galway, the Anderson Bridge is an AC bridge specialised for measuring electrical inductance wherein the unknown inductance value is compared with the capacitance of a fixed reference capacitor. As a modified version of the Maxwell Bridge, it operates in a manner similar to how the Wheatstone Bridge measures resistance. Alexander Anderson's invention enabled precise measurements of inductance ranging from a few microhenrys to several henrys.

G.Hurley, June 3, 2024 All the above changes have been incorporated into the Milestone description.

Re: Re: Comments re: Spelling, Inconsistencies, etc. -- Bberg (talk) 18:45, 5 June 2024 (UTC)

The Milestones Subcommittee met online this morning, and our discussion included this proposal. It was noted that a citation must read correctly apart from its physical location, and thus "Queen's College Galway" must be included, but "here" can still be included. Also, it was noted that the citation lacked a bit of "drama" re: the importance of this invention. In order to include the points above, and including "first invention" re: the "drama," I have reworded the citation, a process that included removing "AC bridge" - how essential is that term, and is it necessary considering our inclusion of Maxwell Bridge?

Please consider the following (68 words):

Developed by Alexander Anderson here at Queen's College Galway, the Anderson Bridge is a modified Maxwell Bridge specialised for measuring electrical inductance by comparing an unknown inductance value with the capacitance of a fixed reference capacitor. While operating in a manner similar to how the Wheatstone Bridge measures resistance, it was the first invention to enable precise measurements of inductance ranging from a few microhenrys to several henrys.

I also note that the 2nd Expert Reviewer is not included on the Comments page, and each Expert must answer the 4 points included in the "Reviewers' Checklist". In addition, to establish their being considered an Expert, some biographical background citing academics, etc., should be included in a statement on that Comments page.

Experts' reviews -- Savini (talk) 11:43, 6 June 2024 (UTC)

Hereby one can se the reviews made by the two qualified experts:

Expert 1

Dear prof. Savini,

Thank you for the consideration. Below my review of the proposal "Milestone-Proposal:Anderson Bridge (2023-05)" you submitted me. Hope it's up to your expectations.

Regards Luca

---

The Anderson bridge is a variation of the Maxwell-Wien bridge (itself a variation of the Wheatstone bridge) designed for the measurement of self-inductance. The benefit is an improved accuracy, the drawback (for the time) a more complex operation and model equation. The bridge was in use until the1950s-1960s, when it was abandoned in favor of electronic LCR meters.

The Anderson bridge is historically relevant, although the same can be said for many other bridge networks (modifications of the Wheatstone bridge) carrying the name of their inventor(s). Hague* gives a least a dozen of schemes sufficiently relevant to have a given name. Of these, at the present time, only the Wheatstone bridge and the Maxwell-Wien bridge are used in impedance metrology.

In my opinion the plaque is justified, although the Wheatstone and the Maxwell-Wien bridges had (and still have) more impact, I don't know if these bridges have already deserved proper recognition from IEEE.

• B. Hague, Alternating current bridge methods, 6th ed. (1971), Pitman Publishing, UK.

1) Is the suggested wording of the Plaque Citation accurate?

I suggest some changes:

"The Anderson Bridge is an ac bridge specialised for the measurement of electrical inductance. The unknown inductance value is compared with the capacitance of a fixed reference capacitor, which is connected between two arms of the bridge. It works in a similarly to the Wheatstone Bridge, used to measure resistance. Anderson's bridge is capable of precise measurements of inductance over a wide range of values from a few microhenry to several henry." (in the SI units are always lowercase, singular).

Regarding the citation of an individual in the plaque, the name "Anderson" is intrinsically linked to the invention and therefore it has to be included.

2) Is the evidence presented in the proposal of sufficient substance and accuracy to support the Citation?

Yes, although the Abstract and the list of IEEE potentially interested societies is missing.

3) Does the proposed milestone represent a significant technical achievement?

Yes, with the caveats expressed in the beginning of my review.

-- Luca Callegaro Istituto Nazionale di Ricerca Metrologica Strada delle Cacce, 91 I-10135 Torino, Italy Google Scholar Book Electrical Impedance: Principles, Measurement, Applications

Expert 2

Dear Antonio,

Thank you for asking me to review this interesting piece of electrical measurement history.

About questions 2) and 3)

I certainly find the “milestone” proposal regarding the Anderson bridge to be relevant and important. I myself am not an expert in inductance measurement, although I am roughly familiar with the bridge used at NPL to calibrate inductance standards. I am more familiar with precision capacitance and resistance measurements where modern techniques enable uncertainties at the 10^-8 level to be routinely achieved with well-defined 3- and 4-terminal standards. Inductance is more difficult, mainly (I believe) due to the extreme difficultly of screening the magnetic fields generated by the wires in the bridge circuit, and the lowest routinely achievable uncertainties are a few 10s of ppm, probably not much lower than in Anderson’s day. Overall, given my understanding of the subject, I find the evidence presented in the proposal to be sufficiently convincing to merit the “milestone” status for Anderson’s bridge.

About question 1)

There was one grammatical error in the plaque text: It works in a similarly to the Wheatstone Bridge, used to measure resistance Is not quite right. Maybe change it to “It works in a similar way to the Wheatstone Bridge…”.

Best regards,

-Stephen

Dr Stephen Giblin Quantum Electrical Metrology Group, Quantum Technologies Department National Physical Laboratory Hampton Road Teddington Middlesex TW11 0LW UK

G. Hurley, June 6, 2024. Citation has been updatged to reflect the comments above regardong location.

Re: Experts' reviews -- Savini (talk) 09:30, 9 June 2024 (UTC)

Replace this text with your reply

Final Advocate's remarks -- Savini (talk) 09:58, 9 June 2024 (UTC)

As the Advocate of the Anderson Bridge proposal, I wish to thank all those who have contributed to the discussion of the proposal. Special thanks are due to the two independent experts whom I selected after the suggestion of eminent academicians in the field of electric measurements. A couple of months ago the qualified experts generously contributed their short, yet clear, reviews reporting their affiliation to Institutions operating in the specific field of metrology in the international context. One of them is the author of the recent scholarly book "Electrical Impedance: Principles, Measurement, Applications, as reported. From these reviews no doubt one can understand that the achievement under discussion is significant and noncontroversial. Therefore I think that the proposal is ready for the decision to be taken by th History Committee.

Re: Final Advocate's remarks -- Bberg (talk) 14:06, 10 June 2024 (UTC)

It should be noted that the proposed citations of each of the expert reviewers as posted on this page most recently by Antonio were older ones, which have been replaced by what is currently on the main page.

G. Hurley, additional comments and short bio, June 10, 2024

Was proposed achievement a significant advance rather than an incremental improvement to an existing technology? The Anderson Bridge was a major advancement on the measurement of inductance at the time, both for accuracy and ease of measurement. Previous attempts were difficult to calibrate. Were there prior or contemporary achievements of a similar nature? The Maxwell Bridge existed at the time, it was considered difficult to calibrate and lacked the expected accuracy. Has the achievement truly led to a functioning, useful, or marketable technology? The Anderson Bridge was considered the equivalent for inductance measurement as the Wheatstone Bridge was for the measurement of resistance. This remained the case until digital methods for measurement evolved in the latter half of the twentieth century

Bio and Technical Background William Gerard Hurley received the B.E. degree in Electrical Engineering from the National University of Ireland, Cork in 1974, the M.S. degree in Electrical Engineering from the Massachusetts Institute of Technology, Cambridge MA, in 1976 and the PhD degree at the National University of Ireland, Galway in 1988 and the higher doctorate D.Eng. degree based on his publications in 2010. He worked for Honeywell Controls in Canada from 1977 to 1979 and for Ontario Hydro from 1979 to 1983. He lectured at the University of Limerick, Ireland from 1983 to 1991 and was professor of Electrical Engineering at the National University of Ireland, Galway until 2017 and is currently professor emeritus at NUI, Galway. He served on the faculty at the Massachusetts Institute of Technology as a Visiting Professor in 1997/1998. Research interests include high frequency magnetics, power quality, and renewable energy systems. Prof. Hurley is a Fellow of the IEEE. He was General Chair of the Power Electronics Specialists Conference in 2000. He is the 2013 recipient of the IEEE PELS Middlebrook Award for Technical Achievement. He was appointed Distinguished Lecturer of the IEEE for 2014/17. He has authored a textbook on magnetics and it was translated into Chinese.