ALD22: Inge Lehmann, Seismologist and Geophysicist

Inge Lehmann

Inge Lehmann

Inge Lehmann was a seismologist and geophysicist who discovered that the Earth has a solid inner core and a molten outer core.

Born in Copenhagen in 1888, in 1907 she began studying mathematics, chemistry and physics at the University of Copenhagen and University of Cambridge, but had to take a break due to ill-health. She resumed her study of mathematics at Cambridge in 1910, before exhaustion enforced another break, eventually restarting her education at Copenhagen University in 1918, graduating in 1920.

Her interest in seismology began when she got a job as an assistant to Niels Erik Nørlund, a geodesist. She was tasked with setting up seismological observatories in Denmark and Greenland, which prompted her to study seismology. She earnt her magister scientiarum, equivalent to a master’s degree, in geodesy in 1928 and took a position as a geodesist and head of the department of seismology at the Geodetical Institute of Denmark. She was responsible for analysing the seismograph data, recording the seismic wave arrival times ready for publication in international bulletins. This data was fundamental to much of the era’s seismological research.

In 1936, she found evidence of P-waves appearing in the shadow of the Earth’s core, which she interpreted as showing that there was an inner core. At the time, it was thought that the Earth’s core was liquid, but an earthquake in New Zealand resulted in P-waves arriving at seismic stations that should have been blocked by this liquid core. Lehmann’s theory was that these P-waves had been refracted by some sort of boundary, which had to mean that there was a solid inner core and a liquid outer core.

Although this interpretation was adopted within a few years, it was not shown to be correct until 1971 when computer calculations using data from more sensitive seismographs could verify her work. Lehmann had to do all of her data collection and calculations by hand, creating boxes of cards, each with data from earthquakes around the world.

Although her work was interrupted by World War II, she served as Chair of the Danish Geophysical Society in both 1940 and 1944.

In the early 1950s, she moved to the US and began investigating the Earth’s crust and upper mantle. A decade later, she discovered a seismic discontinuity, where seismic waves change speeds, at between 190 and 250 km which is now known as the Lehmann Discontinuity. This discovery was made through “exacting scrutiny of seismic records by a master of a black art for which no amount of computerization is likely to be a complete substitute”, as geophysicist Francis Birch put it.

Lehmann received many awards over the years. She was elected as a Fellow of the Royal Society in 1969, was the first woman to win the William Bowie Medal in 1971, and was awarded the Medal of the Seismological Society of America in 1977. The American Geophysical Union began awarding the Inge Lehmann Medal to honour “outstanding contributions to the understanding of the structure, composition, and dynamics of the Earth’s mantle and core” in 1997. In 2015, the asteroid 5632 Ingelehmann was named after her, as was a new beetle species, Globicornis (Hadrotoma) ingelehmannae.

She died in 1993, aged 104.

Further Reading

ALD22: Professor Edith Clarke, Electrical Engineer

Edith Clarke

Professor Edith Clarke

Edith Clarke was an electrical engineer who was the first woman to become a professor of electrical engineering in the USA and developed a method to calculate the maximum power that a transmission line could carry and remain stable.

Clarke was born in Maryland in 1883. After being orphaned at the age of 12, she was raised by her sister and used her inheritance to study mathematics and astronomy at Vassar College. In 1911, she began studying civil engineering at the University of Wisconsin–Madison, but she took a summer job as a human ‘computer’ at AT&T at the end of her first year and enjoyed it so much that she stayed there to train other computers.

She studied electrical engineering at Columbia University in her evenings, then went on to become the first woman to earn a master’s degree in electrical engineering from the Massachusetts Institute of Technology.

She found it difficult to get work as an engineer after graduation, so worked for General Electric, supervising computers. She invented and patented an early graphing calculator, called the Clarke Calculator, which solved equations involving hyperbolic functions ten times faster than other methods.

In 1921, frustrated by a lack of opportunity and equality, Clarke moved to Turkey for a year to teach at the Constantinople Women’s College. When she returned to the USA, GE offered her a position as an electrical engineer, and she became the first professional female electrical engineer in the country.

She also became the first woman to present a paper at the American Institute of Electrical Engineers’ (AIEE) annual meeting. Her paper explained how to calculate the maximum power that a line could carry and remain stable, which became very important as the energy grid grew. The AIEE also awarded her the Best Regional Paper Prize in 1932 and the Best National Paper Prize in 1941, and her work underpinned much of the industry’s understanding of how to deal with power and transmission.

Clarke worked on the West Hoover Dam, developing and installing the hydroelectric turbines.

She also lectured GE engineers, and wrote a textbook based on those lectures, Circuit Analysis of A-C Power Systems, which became a standard text for years. In it, she describes the mathematical methods for addressing power system losses and electrical equipment performance.

In 1947, she became the first female professor of electrical engineering in the USA when she joined the Electrical Engineering Department at the University of Texas at Austin. She taught at Austin until her retirement in 1957

In 1948, she became the first female Fellow of the American Institute of Electrical Engineers, and was the first female full voting member in the American Institute of Electrical Engineers. In 1954, she was given the Society of Women Engineers’ Achievement Award. In 2015, she was posthumously inducted into the National Inventors Hall of Fame.

She died in 1959, aged 76.

Further Reading

ALD22: Professor Flossie Wong-Staal, Virologist and Molecular Biologist

Flossie Wong-Staal

Professor Flossie Wong-Staal

Professor Flossie Wong-Staal, née Wong Yee Ching, 黄以静, was a virologist and molecular biologist who was the first to molecularly clone Human Immunodeficiency Virus (HIV) and created a map of its genes, which was crucial to proving that HIV causes Acquired Immunodeficiency Syndrome (AIDS).

Born in Guangzhou, China, in 1946, she and her family fled to Hong Kong after the Communist Revolution during the late 1940s. When she was 18. Wong-Staal moved to California to study bacteriology at the University of California, Los Angeles, then moved to San Diego for her postdoctoral research before moving to the National Cancer Institute in Maryland in 1973, where she refocused her research on retroviruses.

She discovered that human T-lymphotropic virus, HTLV-1 was the cause of T cell leukaemia, proving that retroviruses can cause human disease. Her work showed that the virus affected human DNA, activating cancer-causing genes called oncogenes.

She went on to work on a new disease that was very similar to HTLV-1, and in 1975, she successfully cloned HIV. She mapped the virus’s genome which both revealed how genetically diverse HIV is, but also allowed the development of blood tests based on detection of the viral genome rather than virus antibodies. She became a world leader in HIV research, studying its genetic structure, replication strategies and regulatory mechanisms.

She published over 400 papers on human retroviruses and AIDSand was the most-cited female scientist of the 1980s. In 1990, the Institute for Scientific Information named her as the top woman scientist of the 1980s.

In 1990, she founded the Centre for AIDS Research at UCSD. Her research focused on gene therapy and on HIV-1’s relationship to Kaposi’s sarcoma, which is a common ailment for people with AIDS.

Wong-Staal became professor emerita upon retirement from UCSD in 2002, and cofounded Immusol (later iTherX Pharmaceuticals), a biopharmaceutical company, becoming its chief scientific officer. She worked there on improving drugs for hepatitis C.

She was inducted into the National Women’s Hall of Fame in 2016, and Discover named her one of the 50 “most extraordinary women scientists” in 2002.

Wong-Staal died on 8 July 2020, aged 73.

Further Reading

ALD22: Nicola Chisholm, Biochemist

Nicola Chisholm

This post was contributed by Chloe Rodgers and is an extract from her Highland Women in STEM project. 

Nicola Chisholm

Nicola Chisholm began her scientific career as a sample administrator at Scottish Water. She then became a Laboratories Team Leader and eventually worked as a scientist there. Her work involved carrying out analytical methods within the cryptosporidium and microbiology departments, determining the qualitative and quantitative taste and odour in raw and potable waters.

She thinks it is important that people realise analytical scientists are required within the water industry, as the majority are unaware of the daily quality control testing to ensure water is safe to drink. Chisholm now works as a scientist at Merck Group.

When asked what could be changed to encourage more girls into STEM, she said:

“Growing up your stereotypical scientist was often a ‘geeky’ man working alone. It’s important that we break this stereotype. It’s necessary that from a young age schools focus on bringing science into the classroom and that society makes a conscious effort to portray female scientists in textbooks, online, on television, wherever! Motivate young girls with female scientists who have accomplished great things so they then gain the curiosity and passion to pursue a career in science. We also need to give girls the knowledge on what’s available work wise in the scientific field and how broad and diverse science can be. There’s industries I continue to learn about that require scientists! So never limit a young girl’s freedom and knowledge and never underestimate them.”

You can follow her work on LinkedIn.

What do you love about your job/course?
I love that my job is a service to public health. When I tell people about my work they are often amazed as they never realised analytical scientists are required and exist in the water industry. Most people don’t know about the essential quality control testing that is ongoing every day to enable safe drinking water. It’s a rewarding feeling knowing you’re doing something to support society.

What do you think could be changed to better encourage more girls into your line of work/a STEM career?
Growing up your stereotypical scientist was often a ‘geeky’ man working alone. It’s important that we break this stereotype. It’s necessary that from a young age schools focus on bringing science into the classroom and that society makes a conscious effort to portray female scientists in textbooks, online, on television, wherever! Motivate young girls with female scientists who have accomplished great things so they then gain the curiosity and passion to pursue a career in science. We also need to give girls the knowledge on what’s available work wise in the scientific field and how broad and diverse science can be. There’s industries I continue to learn about that require scientists! So never limit a young girl’s freedom and knowledge and never underestimate them.

What do you like about the location of your job/course?
Inverness is a fast growing city. New opportunities continue to come here and I hope more scientific industries consider Inverness as the ideal location to base themselves.

Since interviewing, Chisholm has become a senior scientist in a lab in Glasgow.

ALD22: Dr Claudia J Alexander, Geophysicist and Planetary Scientist

Claudia J Alexander

Dr Claudia J Alexander

Dr Claudia J Alexander was a Canadian-American geophysicist and planetary scientist who worked for the United States Geological Survey (USGS) and NASA’s Jet Propulsion Laboratory.

After getting her PhD in atmospheric, oceanic and space sciences, Alexander began working at the USGS studying plate tectonics, then at the Ames Research Center studying Jupiter’s moons. In 1986, she began working at NASA’s Jet Propulsion Laboratory working first as a science coordinator for the plasma instrument on the Galileo spacecraft, before becoming its last mission project manager and overseeing its final plunge into Jupiter’s atmosphere in 2003.

It was during her tenure that Galileo discovered Ganymede’s ionosphere, forcing Alexander to completely rethink her models that showed Ganymede was “frozen solid”. She said of the discovery, “It was an exciting moment to experience something that changed my whole way of thinking. I’ve never been so happy to be wrong before!”

From 2000 until her death, Alexander was in charge of the USA’s contribution to the European Space Agency’s Rosetta mission to study and land on comet Churyumov-Gerasimenko. She was responsible for the instrumentation that collected data such as temperature, as well as overseeing the spacecraft’s tracking and navigation support, which was provided by NASA’s Deep Space Network.

Alexander had a wide variety of interests, studying comet formations, magnetosphere, solar wind, and the planet Venus. She was also a science fiction writer and published children’s books about science under the name EL Celeste.

In 1993, Alexander was named woman of the year by the Association for Women Geoscientists, and in 2003 she received the Emerald Honor for Women of Color in Research & Engineering from Career Communications Group.

In 2015, the Rosetta mission’s team named a gate-like feature on comet Churyumov-Gerasimenko after Alexander, calling it the C Alexander Gate. In 2020, The Division for Planetary Sciences of the American Astronomical Society named a prize for mid-career planetary scientists after her.

Further Reading