The HumanitSEAS

Margaret Robinson and the Thousand Thermoclines

Margaret Robinson did not begin working at the Scripps Institute of Oceanography (SIO) in 1946 for any great love of science.  After earning a Masters degree in languages from UC Berkeley, she was looking for a local job and made her way to Scripps because “there was nowhere else to work.”  She ultimately became a dedicated oceanographer, leading the SIO Bathythermograph unit in developing maps that defined physical oceanography.  During a time when oceanography was considered a “man’s field,” Robinson’s career path is a particularly successful example of female oceanographers operating under decisive gender restrictions.

Athelstan Spilhaus' bathythermograph.  Image from

Athelstan Spilhaus’ bathythermograph. Image from

As Naomi Oreskes explains in her paper “Laissez-tomber: Military Patronage and women’s work in mid-20th-century oceanography,” the origins of SIO’s Bathythermograph Unit can be traced across the country to MIT.  In 1934, MIT professor Dr. Carl-Gustav Rossby created an instrument dubbed the oceanograph.  Athelstan Spilhaus, who was one of Rossby’s graduate students despite a name that suggests he attended Hogwarts, tinkered around with the device and ultimately patented the bathythermograph three years later.  The instrument consisted of a temperature gauge and bellows, with a slice of smoked glass in between (see the photo above).  As the BT was lowered, a pen traced a graph of changing temperature and pressure on the glass; the pressure could later be translated to water depth.  Oceanography was still a relatively new discipline in pre-WWII America, and even basic physical information about the oceans was sorely lacking.  The BT provided a way to measure and map temperature distributions, and because it recorded in detail, it could help oceanographers identify the thermocline- the depth range in which temperatures decrease rapidly.

In the 1940s, scientists weren’t the only ones interested in defining the thermocline.  As the United States entered WWII, the Navy realized that locating the thermocline was crucial to successful operations at sea.  Sonar waves are refracted at a sharp angle in the thermocline, creating a shadow zone where submarines could lie undetected.  The refraction also creates a channel in which sound waves can be transmitted great distances.  The Navy’s SOFAR (Sound Fixing and Ranging System) capitalized on this phenomenon by equipping WWII pilots with devices that could transmit signals through the sound channel, facilitating rescue missions if their plane was shot down.

The shadow zone refers to an area that is not detected by sound waves that are refracted in the thermocline, allowing submarines to "hide" from ships on the surface.  Image from

The shadow zone refers to an area undetected by sound waves refracted by the thermocline, allowing submarines to “hide” from ships on the surface. Image from

Recognizing that knowledge of ocean temperature profiles was necessary for military success, the Navy began adding BTs to ships around 1940.  Thousands of ships were ultimately outfitted with BTs, creating a glut of data that was initially processed by the University of California Division of War Research.  As the war wrapped up in 1945, BT data processing was transferred to SIO in an effort to maintain the connection between the Navy and oceanography- and the funding associated with that collaboration

SIO’s BT unit was staffed mostly by women, with Margaret Robinson entering in 1946 and becoming the head a little over a decade later.  The striking number of women in the unit was symptomatic of the times.   Naomi Oreskes’ paper explains that women were historically relegated to the equivalent of scientific chores: they performed the tedious analytical work eschewed by male scientists.  Oreskes opines that it is too simplistic to assume that all of the boring bits of science were left for women, as the collection of bathythermograph data in the field was entirely dull.  Rather, the division of tasks in oceanography mirrored those in a contemporary family, with men venturing out while women remained on the home front.  This was especially pronounced in oceanography, says Oreskes, due to the influence of seafaring culture and the perception that women would prove too much of a “temptation” on long cruises.  Thus barred from conducting fieldwork, prospective female scientists filled whatever positions they could wedge their way into- and in the 1950s and 60s, that included most of the jobs in the SIO BT unit.  Employees were charged with translating the temperature-pressure graphs into maps and charts that could be used by the Navy.  The work required tremendous patience, as the ultimate product was the result of careful analysis of thousands of BT deployments.

Margaret Robinson at work at the Scripps Oceanography Institute's Bathythermograph Unit.  Image from

Margaret Robinson at work at the Scripps Oceanography Institute’s Bathythermograph Unit. Image from

One of the most prominent members of the BT unit, Margaret Robinson received an MS degree in physical oceanography despite discouragement from one of the people most closely associated with the field: Harald Sverdrup, the SIO director at the time.  Oreskes’ paper describes that, when Robinson told Sverdrup that she hoped to become an oceanographer, the latter replied, “My dear Mrs. Robinson, this is a man’s field.  You would never be accepted.”  Well, here’s to you, Mrs. Robinson, because she used her work in the BT unit to earn her MS from the University of California in 1951.  During her career, Robinson also advised the Thai Royal Navy in developing their hydrographic systems and convinced SIO to purchase computers for the BT unit.  Robinson’s 2006 obituary in the U-T San Diego further notes that she went out of her way to encourage female employees, offering extra flexibility so they could balance their family obligations with work.

Margaret Robinson was surely not the only exemplary female scientist working in SIO’s BT unit.  It’s vital to recognize her accomplishments, which far eclipsed the opportunities enjoyed by most mid-century women and speak to her particular tenacity.  However, it’s also useful to reflect on the many would-be female scientists of the time, confined to processing smoked glass slides when they would have preferred to collect field data or lead experiments, and to realize that Robinson may have gone on to even greater renown had the doors been open to her.  As we continue to discuss women in science, I would like to propose a new conversation point: with apologies to dear Mr. Sverdrup, who’s up for renaming it Robinson transport?

For more info:

Oreskes, Naomi. Laissez-tomber: Military patronage and women’s work in mid-20th-century oceanography. Historical Studies in the Physical and Biological Sciences 30(2): 373-392.

Margaret Robinson biography from Scripps:

Margaret Robinson’s obituary in U-T San Diego:


2 thoughts on “Margaret Robinson and the Thousand Thermoclines

  1. Pingback: The Manzanar Project and the World’s Most Unlikely Mangroves | UNder the C

  2. Pingback: Ruth Patrick’s Aquatic Pollution Revolution | UNder the C

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