Mabel MacFerran Rockwell

Mabel MacFerran was born in Philadelphia, Pennsylvania, in 1902 to Edgar O. and Mabel Alexander MacFerran.{{Cite book |last=Goff |first=Alice C. |title=Women Can Be Engineers |publisher=Edward Brothers, Inc. |year=1946 |location=Youngstown, Ohio |pages=94–112}} Her father was a scientist and her mother an astronomer and mathematician. She was raised in the Quaker tradition.{{Cite news |date=January 30, 1949 |title=Scientist Warns: Enough Atomics; Now for Soul |work=Los Angeles Times |pages=3}}

She attended the Germantown Friends School in Germantown, Pennsylvania. While studying at Bryn Mawr College, she had a summer job with the Leeds and Northrup Company, which introduced her to engineering. She transferred to the Massachusetts Institute of Technology. In 1925, she graduated first in her class at MIT with a Bachelor of Science in mathematics.{{Cite book |last=Mitnick |first=Steve |url=https://www.fortnightly.com/sites/default/files/article_uploads/Women_Leading_Utilities.pdf |title=Women Leading Utilities: The Pioneers and Path to Today and Tomorrow |publisher=Lines Up, Inc. |year=2021 |isbn=978-1-7360142-3-3 |pages=37}} She moved to California, becoming the Elwell Fellow at Stanford University and working with Professor Harris J. Ryan in the million volt laboratory. She obtained an M.S. degree in electrical engineering from Stanford in 1926.{{Cite journal |title=Notes About Contributors in This Issue |journal=Metal Progress |volume=41 |issue=June |pages=860}}

MacFerran married fellow engineer Edward W. Rockwell on June 7, 1935. Because they were both members of the AIEE, the society's journal Electrical Engineering deemed the event newsworthy and published an account in the July 1935 issue. The Rockwells became the fourth couple where both partners were members of the society. At the time, there were only nine female members of the AIEE.{{Cite journal |date=1935 |title=A Marriage Between 2 Institute Members |url=https://ieeexplore.ieee.org/document/6538957/;jsessionid=299EE4358574886C88677DD283802340 |journal=Electrical Engineering |volume=54 |issue=7 |pages=787 |doi=10.1109/EE.1935.6538957 |issn=2376-7804|url-access=subscription }}

The Rockwells had one daughter, Margaret Alice, in 1936.{{Cite web |date=July 27, 1941 |title=Bristol Herald Courier from Bristol, Tennessee |url=https://www.newspapers.com/newspage/584712297/ |access-date=May 11, 2025 |website=Newspapers.com |language=en-US}} MacFerran and Rockwell divorced in 1958.

MacFerran enjoyed the sports of tennis, hiking, and sailing, as well as driving cars very fast. She would also relax with a good murder mystery.

She died in Mountain View, California, on May 27, 1979, at the age of 77.{{Cite news |date=June 7, 1979 |title=Obituary for Mabel Rockwell |url=https://www.newspapers.com/article/the-san-francisco-examiner-obituary-for/176066094/ |access-date=July 6, 2025 |work=The San Francisco Examiner |pages=51}} A memorial service was held at Stanford Memorial Church.{{Cite news |date=June 7, 1979 |title=Mabel Macferran Rockwell, 1958's Woman Engineer |work=The Fresno Bee |pages=63}}

MacFerran became an associate member of the American Institute of Electrical Engineers (AIEE) in 1928, one of the first ten women to join the professional association.{{Cite journal |date=1934 |title=List of women members of the A.I.E.E. |url=https://ieeexplore.ieee.org/document/6541647 |journal=Electrical Engineering |volume=53 |issue=5 |pages=835 |doi=10.1109/EE.1934.6541647 |issn=2376-7804}} She became an AIEE member in 1935.{{Cite journal |date=1935 |title=Personal items |url=https://ieeexplore.ieee.org/document/6540196 |journal=Electrical Engineering |volume=54 |issue=9 |pages=1018–1022 |doi=10.1109/EE.1935.6540196 |issn=2376-7804|url-access=subscription }}

In 1926 MacFerran joined the Southern California Edison Company Limited as an apprentice testman, becoming the technical assistant to the operating engineer in 1928. She specialized in studies of high voltage power transmission and system stability. She made one of the earliest applications of the method of symmetrical components to power systems.

Along with Roy B. Ashbrook, Roy Edwin Quanstrom, and Benjamin F. Dengler, Macferran received {{US Patent|1,889,086}} (filed December 30, 1929, granted November 29, 1932) for a "Protective Gap for Electrical Equipment" which became known as the "Serjdetour" telephone protector.{{Cite journal |last=Hoh |first=Yin Kiong |title=Outstanding women in mechanical engineering |url=http://cristianbeaty.pbworks.com/w/file/fetch/52165005/nyanyanyanyanyanyan.pdf |journal=International Journal of Mechanical Engineering Education |volume=35 |issue=3 |pages=204}}

In 1932 she became an assistant electrical engineer of the Metropolitan Water District of Southern California at Los Angeles. She worked on electrical problems with the Colorado River Aqueduct, including economic and engineering studies for the construction power system and the main transmission system. Macferran was the only woman to work on the design and installation of the electrical systems, specifically the power generating equipment, for Boulder Dam (later renamed Hoover Dam). She worked on the economic design of the company's transmission for the dam, which was the basis for her prize-winning paper "Power Limits of 220 Kv Transmission Lines" (co-authored with A. A. Kroneberg). She also designed the transmission and distribution systems for the San Joaquin Valley District in California.

In 1938 she became the Plant Electrical Engineer for the Lockheed Aircraft Corporation (Lockheed Corporation) and in 1940 became Production Research Engineer. She led a research team that improved spot welding for aircraft production. She then turned her team's focus to the problems of forming sheet metal airplane parts, publishing a series of articles on this research.

From 1946 to 1957 she worked for the US Civil Service. From 1951 to 1953, she was an electrical engineer with the United States Bureau of Reclamation in Sacramento, California and Fresno, California. She was chief of the power section in the San Joaquin Valley district office in Fresno.

After WWII, she went to work for Westinghouse where she designed the electrical control system for the UGM-27 Polaris missile launcher.{{Cite book |last1=Wang |first1=Katherine T. |title=Women in Renewable Energy |last2=Tietjen |first2=Jill S. |publisher=Springer}} Despite her work in the field, by 1949 she was advocating for a turn from weapons development to working for peace. In an interview with the LA Times, she said: "We know enough about the atom—now it's time for intelligent men everywhere to develop spiritual values. Americans must halt their pursuit of more technical knowledge and devote their time to the elimination of war by turning from things of the mind to things of the spirit."

In 1929 she won the Initial Paper Prize in the AIEE 8th District for her paper "Parallel Operation of Transformers Whose Ratios of Transformation are Unequal."{{Cite journal |date=1930 |title=A. I. E. E. section activities |url=https://ieeexplore.ieee.org/document/6536385 |journal=Journal of the A.I.E.E. |volume=49 |issue=10 |pages=888 |doi=10.1109/JAIEE.1930.6536385 |issn=2376-5976}}

In 1934 she won the AIEE Pacific District prize for "Power Limits of 220 Kv Transmission Lines" with co-author A. A. Kroneberg.

In 1958 President Eisenhower named her Woman Engineer of the Year.

In 1959, she won the SWE Achievement Award from the Society of Women Engineers "in recognition of her significant contributions to the field of electrical control systems."{{Cite web |date=October 20, 2024 |title=SWE Awards |url=https://ethw.org/SWE_Awards |access-date=May 11, 2025 |website=ETHW |language=en}}

She was a member of Sigma Xi.

• "Parallel Operation of Transformers Whose Ratios of Transformation are Unequal", 1930{{Cite journal |last=Macferran |first=Mabel |date=1930 |title=Parallel Operation of Transformers Whose Ratios of Transformation are Unequal |url=https://ieeexplore.ieee.org/document/5055467/;jsessionid=525BD375896F8F866D8B03FD3FCD3A1C |journal=Transactions of the American Institute of Electrical Engineers |volume=49 |issue=1 |pages=125–131 |doi=10.1109/T-AIEE.1930.5055467 |issn=2330-9431|url-access=subscription }}
• "Power Limits of 220-Kv Transmission Lines" (with Alex A. Kroneberg), 1934{{Cite journal |last1=Kroneberg |first1=Alex A. |last2=Macferran |first2=Mabel |date=1934 |title=Power Limits of 220-Kv Transmission Lines |url=https://ieeexplore.ieee.org/document/5056602/;jsessionid=7372D8EE504790F4BF38DA5682AA1832 |journal=Transactions of the American Institute of Electrical Engineers |volume=53 |issue=12 |pages=1794–1802 |doi=10.1109/T-AIEE.1934.5056602 |issn=2330-9431|url-access=subscription }}
• "Empirical Method of Calculating Corona Loss From High-Voltage Transmission Lines" (with Joseph S. Carroll), 1937{{Cite journal |last1=Carroll |first1=Joseph S. |last2=Rockwell |first2=Mabel Macferran |date=1937 |title=Empirical method of calculating corona loss from high-voltage transmission lines |url=https://ieeexplore.ieee.org/document/6539813/;jsessionid=52190A61ABE59701866378987A83C058 |journal=Electrical Engineering |volume=56 |issue=5 |pages=558–565 |doi=10.1109/EE.1937.6539813 |issn=2376-7804|url-access=subscription }}
• "Empirical Method of Calculating Corona Loss From High-Voltage Transmission Lines" (published discussion with E. C. Starr and author), 1938{{Cite journal |last1=Carroll |first1=Joseph H. |last2=Rockwell |first2=Mabel Macferran |date=1938 |title=Empirical method of calculating corona loss from high-voltage transmission lines |url=https://ieeexplore.ieee.org/document/6431191/;jsessionid=BC0819DBFE17D5E9C29CAE0BA45D3DBD |journal=Electrical Engineering |volume=57 |issue=3 |pages=168–169 |doi=10.1109/EE.1938.6431191 |issn=2376-7804|url-access=subscription }}
• "The Development of Aircraft Spotwelding", 1941{{Cite journal |last=Rockwell |first=Mabel M. |date=1941 |title=The Development of Aircraft Spotwelding |journal=Aviation |volume=40 |issue=July |pages=42–43}}
• "Mechanics of Deep Drawing Sheet Metal Parts" (with Given Brewer), 1942{{Cite journal |last1=Brewer |first1=Given |last2=Rockwell |first2=Mrs. Mabel MacFerran |date=1942 |title=Mechanics of Deep Drawing Sheet Metal Parts |journal=Aero Digest |volume=40 |issue=February |pages=126–135}}
• "Stretch-Forming Contoured Sheet Metal Aircraft Parts" (with T. H. Hazlett), 1942{{Cite journal |last1=Hazlett |first1=T. H. |last2=Rockwell |first2=Mabel |date=1942 |title=Stretch-Forming Contoured Sheet Metal Aircraft Parts |journal=The Iron Age |volume=149 |issue=June 4 |pages=49–53}}
• "Measurements of Drawing Properties of Aluminum Sheet" (with Given A. Brewer), 1942{{Cite journal |last1=Brewer |first1=Given A. |last2=Rockwell |first2=Mabel M. |date=1942 |title=Measurements of Drawing Properties of Aluminum Sheet |journal=Metal Progress |volume=41 |issue=May |pages=663–668}}
• "Stress-Strain Relationships in Drawing of Materials" (with G. A. Brewer), 1942{{Cite journal |last1=Brewer |first1=G. A. |last2=Rockwell |first2=M. M. |date=1942 |title=Stress-Strain Relationships in Drawing of Materials |journal=Metal Progress |volume=41 |issue=June |pages=806–810}}
• "Some Factors Affecting the Drawability of Aluminum Sheets" (with G. A. Brewer and V. N. Krivobok), 1942{{Cite journal |last1=Brewer |first1=G. A. |last2=Krivobok |first2=Allison |last3=Rockwell |first3=Mabel M. |date=1942 |title=Some Factors Affecting the Drawability of Aluminum Sheets |journal=Metal Progress |volume=42 |issue=July |pages=62–65}}
• "The Effect of Weld Spacing on the Strength of Spot-Welded Joints" (with R. Della-Vedowa), 1942{{Cite journal |last1=Della-Vedowa |first1=R. |last2=Rockwell |first2=M. M. |date=1942 |title=The Effect of Weld Spacing on the Strength of Spot-Welded Joints |journal=The Welding Journal |volume=21 |issue=10 |pages=514-s-523-s}}
• "Electrical Power in Aircraft", 1944{{Cite journal |last=Rockwell |first=Mabel Macferran |date=1944 |title=Electric power in aircraft |url=https://ieeexplore.ieee.org/document/6440549/;jsessionid=940769417C8A8ECC87F574F92AD6A88A |journal=Electrical Engineering |volume=63 |issue=11 |pages=400–402 |doi=10.1109/EE.1944.6440549 |issn=2376-7804|url-access=subscription }}

{{Reflist}}

Johnson, Vicki (2025). Chapter 10 "Mabel MacFerran Rockwell". In Craig, Cecilia; Teig, Holly; Kimberling, Debra; Williams, Janet; Tietjen, Jill; Johnson, Vicki (eds.). Women Engineering Legends 1952-1976: Society of Women Engineers Achievement Award Recipients. Springer Cham. ISBN9783032002235

• {{patent|US|1889086|"Protective Gap for Electrical Equipment"}}

{{Authority control}}

Category:Massachusetts Institute of Technology alumni

Category:Stanford University School of Engineering alumni

Category:Bryn Mawr College people

Category:Women electrical engineers

Category:Members of the IEEE

Category:Achievement Award Recipients of the Society of Women Engineers

Category:Members of the Society of Women Engineers