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Making "The Chart of Electromagnetic Radiations"

Even a small portion of the comprehensive Chart of Electromagnetic
Radiations is crammed full of science.
About a month ago, the Lawrence Livermore lab posted this gorgeous old poster of the electromagnetic spectrum onto its Flickr page. It's an amazing artifact of scientific education from 1944, complete with  images of retro radio equipment, hospital radium rays and one of the first commercially available television set.

Putting together a chart like this can be as much of an undertaking as publishing a book. It's an under-appreciated art form, and sometimes takes a coordinated team of editors, designers and consultants years to produce a final product.

The driving force behind its creation in the late 1930s was Dwight Barr, a consultant for the W. M. Welch Scientific Company. He spent two years of his life designing and editing it, with the project at times taking over part of his house. Once published, nearly every major university and scientific institution bought a copy.

Science was Barr's great passion, and he spent most of his life sharing that passion with others. He collected samples of nearly all the 92 naturally occurring elements, and convinced Chicago's Museum of Science and Industry to start a collection of their own. He once punched a hole in the wall of his home so the planets in his scale model of the solar system would be at precisely the right distance from the sun. He was the quintessential high school science teacher.

Born in 1904, Barr grew up in Gibson City Illinois. When he was 12, his older brother picked up an early spark-gap transmitter, the first kind of amateur radios, and the two of them started broadcasting with it. Playing and tinkering with the machine fascinated him, and he kept his radio handle "sparky" for the rest of his life.

The small house Barr and his friends built and lived in
 while attending college. Image: The Barr Family
Barr was always building things. When he went away to college, he decided to study science at the University of Illinois at Urbana-Champaign. Instead of living in a dorm while at school, he and a few friends pooled their money and bought a small piece of land at the outskirts of town. They constructed a small shack not much bigger than the triple bunk bed they shared, and lived there for the five years they attended the university.

After graduating, he started teaching high school science in small central Illinois town of Pulaski. He stayed there for a few years, helping run the school's science clubs, until in 1933 he pulled up stakes and applied for a teaching position at the J. Sterling Morton High School in Cicero, on the outskirts of Chicago. It was lucky he got it because quitting his job and moving across the state was a bold move in 1933. The Great Depression was in full swing and there was no guarantee he would find a job there.

Though he loved teaching, the salary of a high school teacher alone wasn't quite enough for, his wife and four children to live off. He started consulting with the W. M. Welch Scientific Company, on the weekends, helping to review textbooks and design experiment kits for classrooms.

A few years earlier, Welch had produced a chart of the periodic table of the elements that was a smash success. High schools and colleges across the country bought copies and Welch was looking to capture lightning in a bottle again.

While teaching at Morton, Barr found his inspiration for what would become his masterpiece of science infographics, the Chart of Electromagnetic Radiations. For an art project, a young student of his cut out magazine pictures of radio towers, light bulbs and X-ray machines, arranging them along a ten-foot roll of butcher paper in order of their wavelengths. She won a prize for her work at the Illinois Junior Academy of Science. A year later another student of his took the idea a step farther, and hand-drew all of the different transmitters and receivers. Barr brought the idea for an electromagnetic chart to the Welch company.

Putting together a chart about electromagnetism that would appeal to everyone was not an easy task. Barr traveled to Washington DC to collaborate with the secretary of the National Bureau of Standards,  Henry Hubbard, who also edited the popular elements poster. They started collaborating, but when Barr returned home to Illinois, Hubbard sent word that he didn't want his name included on the chart. It wasn't because he was unhappy with the the way it was turning out, but because Barr had contributed so much more, Hubbard didn't think it fair to include himself.

The Welch Company went in search of another big name to attach to the project, and got in touch with Nobel laureate Arthur Compton. Compton agreed to be named the editor, though in practice it was Compton's assistant R. J. Stephenson who did most of the actual advising.

Dwight L. Barr.
Image: The Barr Family
Stephenson took what Barr and Hubbard had put together and completely reorganized it. After seeing what had been done, Barr was disconsolate, until a colleague said to him, "If it's yours, why don't you do what you want to do?" He reorganized it back to reflect more of his original vision.

Barr clashed also with the artist E. Borsone. There was so much about radiation to be included, that it was hard to strike a balance between being being comprehensive and being comprehensible. Borsone wanted to give the images more space, to "let them breathe," while Barr wanted to put as much together as possible.

It takes a lot of space to organize the master copy of a five-foot-wide chart. Barr's children remember having to tiptoe around the rough copy which took up the whole living room floor.

After two years of work the chart was just about finished, but right up until the end Barr was adding more to it. Shortly before before it was ready for its first printing, RCA released its first commercial television set with a cathode ray tube, instead of the older spinning "scan disk" designs. Not wanting the chart to be outdated before it was even printed, Barr stopped the presses while they drew up an updated television set.

The Chart of Electromagnetic Radiations debuted at the 1936 meeting of the American Association for the Advancement of Science in Indianapolis. The first reviews of the dense chart were a bit discouraging. After it was unveiled a scientist came up to Barr and asked him, "Do you furnish headache pills with that chart?"

Though the chart never sold as well to high schools as the earlier periodic table chart, it was a big hit with colleges and laboratories. Glimpses of it can often be seen in the backgrounds of educational films and even hollywood films like Steve Martin's The Man With Two Brains and Disney's The Computer Wore Tennis Shoes. One made its way to Lawrence Livermore National Labs whose preservation of it means we can see it today.

Barr continued working with the Welsh company for decades. He wrote up a teacher's guide that went with the chart, and also designed several classroom demonstrations about electromagnetism that were also sold by the company. He said years later that he always wanted to return to the chart and update it to include lasers and radar, but the company never opted to revise it.


  1. I really like to read this whole content about Electromagnetic Radiations. Chart of Electromagnetic Radiations is excellent and easily understandable.

  2. It´s a really interesting story. Where did you find all this information about Barr and his biograhy?

  3. Excellent work compiling this backstory! I've posted a "dusted-off" version of the chart which fixes some of the color issues:

  4. He taught physics at Prosper h.s. Chicago

  5. He was my physics teacher in high school

  6. I have an original 1938 copy of this chart.


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