Simanaitis Says

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AS DESCRIBED here yesterday, the 1878 solar eclipse didn’t exactly further astronomer James Craig Watson’s search for the planet Vulcan. Today, we’ll look at the 1878 eclipse again and find perhaps less than satisfying successes for Thomas Edison and his tasimeter and then for Maria Mitchell and her women’s march to Denver. On the other hand, each of these tales ends happily.

Thomas Alva Edison, 1847–1931, American inventor and businessman, with his phonograph. Image by Mathew Brady, 1878.

Thomas Edison was 31 in 1878 and had yet to invent the electric light bulb (his first success with this came a year later). For the eclipse, though, he had his tasimeter, a gizmo capable of measuring small variations in temperature.

The Edison tasimeter.

The tasimeter functioned through expansion and contraction of a rod of vulcanite, which in turn changed the resistance of a linked electrical circuit.

Vulcanite, not to be confused with yesterday’s planet Vulcan, is a rare copper telluride mineral; the Colorado city Telluride gets its name from telluride, a tellurium anion Te2– and its derivatives, analogous to other chalcogenide anions. I’m glad we got that settled.

Jennifer Carson said in her Science review “The Sun Spotters” that Edison used his tasimeter in the 1878 eclipse to measure temperature variations of the sun’s corona, the ring remaining during totality. It worked, but it didn’t prove nearly as memorable as Edison’s next success: the electric light bulb.

The solar eclipse of January 4, 2011, as photographed from the Hinode satellite. Image from Science, July 17, 2017.

Maria (pronounced ma-RYE-ah) Mitchell was the first American woman to work as a professional astronomer. Reviewer Carson stresses it was at “a time when women did not have the right to vote and experienced crushing misogyny.”

Maria Mitchell, 1818–1889, American astronomer, discoverer of Miss Mitchell’s Comet, 1847. This and the following image from Maria Mitchell Association.

Indeed, Mitchell was first in 1847 in an annual competition to discover a “telescopic comet,” that is, one so faint as to be visible only through a telescope. Initially known as Miss Mitchell’s Comet, it’s now designated C/1847 T1. This discovery earned Mitchell a gold medal from King Frederick IV of Denmark. I uncovered no such honor bestowed by James K. Polk, U.S. President at the time.

Maria Mitchell’s gold medal from Denmark’s King Frederick IV.

In 1878, Mitchell led a group of women to Denver, both to record the eclipse and, in the larger sense, to make visible the role of women in professional science. Cites reviewer Carson, “Mitchell’s expedition, while a political achievement, ‘produced no great scientific discoveries,’ ” according to American Eclipse author David Baron.

Geez, talk about misogyny.

On the other hand, Mitchell had been the first woman elected a Fellow of the American Academy of Arts and Science in 1848. Two years later, she was similarly honored by the American Association for the Advancement of Science (the organization publishing the weekly Science magazine).

In 1865, she became Professor of Astronomy at Vasser and was named Director of the Vassar College Observatory. According to the Vassar Encyclopedia, Mitchell learned years later that, despite her experience and reputation, her salary was less than that of many younger male professors. She demanded a raise—and got it.

In summary, no planet Vulcan for Watson, no tasimeter fame for Edison, and “no great scientific discoveries” for Mitchell. On the other hand, a productive lifetime in science depends on more than a single experiment. ds

© Dennis Simanaitis,, 2017

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