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Why Some Civil War Soldiers Glowed in the Dark

By the spring of 1862, a year into the American Civil War, Major General Ulysses S. Grant had pushed deep into Confederate territory along the Tennessee River. In early April, he was camped at Pittsburg Landing, near Shiloh, Tennessee, waiting for Maj. Gen. Don Carlos Buell’s army to meet up with him.

On the morning of April 6, Confederate troops based out of nearby Corinth, Mississippi, launched a surprise offensive against Grant’s troops, hoping to defeat them before the second army arrived. Grant’s men, augmented by the first arrivals from the Ohio, managed to hold some ground, though, and establish a battle line anchored with artillery. Fighting continued until after dark, and by the next morning, the full force of the Ohio had arrived and the Union outnumbered the Confederates by more than 10,000.

The Union troops began forcing the Confederates back, and while a counterattack stopped their advance it did not break their line. Eventually, the Southern commanders realized they could not win and fell back to Corinth until another offensive in August (for a more detailed explanation of the battle, see this animated history).

All told, the fighting at the Battle of Shiloh left more than 16,000 soldiers wounded and more 3,000 dead, and neither federal or Confederate medics were prepared for the carnage.

The bullet and bayonet wounds were bad enough on their own, but soldiers of the era were also prone to infections. Wounds contaminated by shrapnel or dirt became warm, moist refuges for bacteria, which could feast on a buffet of damaged tissue. After months marching and eating field rations on the battlefront, many soldiers’ immune systems were weakened and couldn’t fight off infection on their own. Even the army doctors couldn’t do much; microorganisms weren’t well understood and the germ theory of disease and antibiotics were still a few years away. Many soldiers died from infections that modern medicine would be able to nip in the bud.

A Bright Spot

Some of the Shiloh soldiers sat in the mud for two rainy days and nights waiting for the medics to get around to them. As dusk fell the first night, some of them noticed something very strange: their wounds were glowing, casting a faint light into the darkness of the battlefield. Even stranger, when the troops were eventually moved to field hospitals, those whose wounds glowed had a better survival rate and had their wounds heal more quickly and cleanly than their unilluminated brothers-in-arms. The seemingly protective effect of the mysterious light earned it the nickname “Angel’s Glow.”

In 2001, almost one hundred and forty years after the battle, seventeen-year-old Bill Martin was visiting the Shiloh battlefield with his family. When he heard about the glowing wounds, he asked his mom - a microbiologist at the USDA Agricultural Research Service who had studied luminescent bacteria that lived in soil - about it.

“So you know, he comes home and, 'Mom, you're working with a glowing bacteria. Could that have caused the glowing wounds?’” Martin told Science Netlinks. “And so, being a scientist, of course I said, ‘Well, you can do an experiment to find out.’”

And that’s just what Bill did.

He and his friend, Jon Curtis, did some research on both the bacteria and the conditions during the Battle of Shiloh. They learned that Photorhabdus luminescens, the bacteria that Bill’s mom studied and the one he thought might have something to do with the glowing wounds, live in the guts of parasitic worms called nematodes, and the two share a strange lifecycle. Nematodes hunt down insect larvae in the soil or on plant surfaces, burrow into their bodies, and take up residence in their blood vessels. There, they puke up the P. luminescens bacteria living inside them. Upon their release, the bacteria, which are bioluminescent and glow a soft blue, begin producing a number of chemicals that kill the insect host and suppress and kill all the other microorganisms already inside it. This leaves P. luminescens and their nematode partner to feed, grow and multiply without interruptions.

As the worms and the bacteria eat and eat and the insect corpse is more or less hollowed out, the nematode eats the bacteria. This isn’t a double cross, but part of the move to greener pastures. The bacteria re-colonize the nematode’s guts so they can hitch a ride as it bursts forth from the corpse in search of a new host.

The next meal shouldn’t be hard to find either, since P. luminescens already sent them an invitation to the party. Just before they got got back in their nematode taxi, P. luminescens were at critical mass in the insect corpse, and scientists think that that many glowing bacteria attract other insects to the body and make the nematode’s transition to a new host much easier.

A Good Light

Looking at historical records of the battle, Bill and Jon figured out that the weather and soil conditions were right for both P. luminescens and their nematode partners. Their lab experiments with the bacteria, however, showed that they couldn’t live at human body temperature, making the soldiers’ wounds an inhospitable environment. Then they realized what some country music fans already knew: Tennessee in the spring is green and cool. Nighttime temperatures in early April would have been low enough for the soldiers who were out there in the rain for two days to get hypothermia, lowering their body temperature and giving P. luminescens a good home.

Based on the evidence for P. luminescens’s presence at Shiloh and the reports of the strange glow, the boys concluded that the bacteria, along with the nematodes, got into the soldiers’ wounds from the soil. This not only turned their wounds into night lights, but may have saved their lives. The chemical cocktail that P. luminescens uses to clear out its competition probably helped kill off other pathogens that might have infected the soldiers’ wounds. Since neither P. luminescens nor its associated nematode species are very infectious to humans, they would have soon been cleaned out by the immune system themselves (which is not to say you should be self-medicating with bacteria; P. luminescens infections can occur, and can result in some nasty ulcers). The soldiers shouldn’t have been thanking the angels so much as the microorganisms.

As for Bill and Jon, their study earned them first place in team competition at the 2001 Intel International Science and Engineering Fair.

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Travel Salem via Flickr // CC BY-ND 2.0
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A.C. Gilbert, the Toymaker Who (Actually) Saved Christmas 
Travel Salem via Flickr // CC BY-ND 2.0
Travel Salem via Flickr // CC BY-ND 2.0

Alfred Carlton Gilbert was told he had 15 minutes to convince the United States government not to cancel Christmas.

For hours, he paced the outer hall, awaiting his turn before the Council of National Defense. With him were the tools of his trade: toy submarines, air rifles, and colorful picture books. As government personnel walked by, Gilbert, bashful about his cache of kid things, tried hiding them behind a leather satchel.

Finally, his name was called. It was 1918, the U.S. was embroiled in World War I, and the Council had made an open issue about their deliberation over whether to halt all production of toys indefinitely, turning factories into ammunition centers and even discouraging giving or receiving gifts that holiday season. Instead of toys, they argued, citizens should be spending money on war bonds. Playthings had become inconsequential.

Frantic toymakers persuaded Gilbert, founder of the A.C. Gilbert Company and creator of the popular Erector construction sets, to speak on their behalf. Toys in hand, he faced his own personal firing squad of military generals, policy advisors, and the Secretary of War.

Gilbert held up an air rifle and began to talk. What he’d say next would determine the fate of the entire toy industry.

Even if he had never had to testify on behalf of Christmas toys, A.C. Gilbert would still be remembered for living a remarkable life. Born in Oregon in 1884, Gilbert excelled at athletics, once holding the world record for consecutive chin-ups (39) and earning an Olympic gold medal in the pole vault during the 1908 Games. In 1909, he graduated from Yale School of Medicine with designs on remaining in sports as a health advisor.

But medicine wasn’t where Gilbert found his passion. A lifelong performer of magic, he set his sights on opening a business selling illusionist kits. The Mysto Manufacturing Company didn’t last long, but it proved to Gilbert that he had what it took to own and operate a small shingle. In 1916, three years after introducing the Erector sets, he renamed Mysto the A.C. Gilbert Company.

Erector was a big hit in the burgeoning American toy market, which had typically been fueled by imported toys from Germany. Kids could take the steel beams and make scaffolding, bridges, and other small-development projects. With the toy flying off shelves, Gilbert’s factory in New Haven, Connecticut grew so prosperous that he could afford to offer his employees benefits that were uncommon at the time, like maternity leave and partial medical insurance.

Gilbert’s reputation for being fair and level-headed led the growing toy industry to elect him their president for the newly created Toy Manufacturers of America, an assignment he readily accepted. But almost immediately, his position became something other than ceremonial: His peers began to grow concerned about the country’s involvement in the war and the growing belief that toys were a dispensable effort.

President Woodrow Wilson had appointed a Council of National Defense to debate these kinds of matters. The men were so preoccupied with the consequences of the U.S. marching into a European conflict that something as trivial as a pull-string toy or chemistry set seemed almost insulting to contemplate. Several toy companies agreed to convert to munitions factories, as did Gilbert. But when the Council began discussing a blanket prohibition on toymaking and even gift-giving, Gilbert was given an opportunity to defend his industry.

Before Gilbert was allowed into the Council’s chambers, a Naval guard inspected each toy for any sign of sabotage. Satisfied, he allowed Gilbert in. Among the officials sitting opposite him were Secretary of War Newton Baker and Secretary of the Navy Josephus Daniels.

“The greatest influences in the life of a boy are his toys,” Gilbert said. “Yet through the toys American manufacturers are turning out, he gets both fun and an education. The American boy is a genuine boy and wants genuine toys."

He drew an air rifle, showing the committee members how a child wielding less-than-lethal weapons could make for a better marksman when he was old enough to become a soldier. He insisted construction toys—like the A.C. Gilbert Erector Set—fostered creative thinking. He told the men that toys provided a valuable escape from the horror stories coming out of combat.

Armed with play objects, a boy’s life could be directed toward “construction, not destruction,” Gilbert said.

Gilbert then laid out his toys for the board to examine. Secretary Daniels grew absorbed with a toy submarine, marveling at the detail and asking Gilbert if it could be bought anywhere in the country. Other officials examined children’s books; one began pushing a train around the table.

The word didn’t come immediately, but the expressions on the faces of the officials told the story: Gilbert had won them over. There would be no toy or gift embargo that year.

Naturally, Gilbert still devoted his work floors to the production efforts for both the first and second world wars. By the 1950s, the A.C. Gilbert Company was dominating the toy business with products that demanded kids be engaged and attentive. Notoriously, he issued a U-238 Atomic Energy Lab, which came complete with four types of uranium ore. “Completely safe and harmless!” the box promised. A Geiger counter was included. At $50 each, Gilbert lost money on it, though his decision to produce it would earn him a certain infamy in toy circles.

“It was not suitable for the same age groups as our simpler chemistry and microscope sets, for instance,” he once said, “and you could not manufacture such a thing as a beginner’s atomic energy lab.”

Gilbert’s company reached an astounding $20 million in sales in 1953. By the mid-1960s, just a few years after Gilbert's death in 1961, it was gone, driven out of business by the apathy of new investors. No one, it seemed, had quite the same passion for play as Gilbert, who had spent over half a century providing fun and educational fare that kids were ecstatic to see under their trees.

When news of the Council’s 1918 decision reached the media, The Boston Globe's front page copy summed up Gilbert’s contribution perfectly: “The Man Who Saved Christmas.”

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The Queen of Code: Remembering Grace Hopper
By Lynn Gilbert, CC BY-SA 4.0, Wikimedia Commons

Grace Hopper was a computing pioneer. She coined the term "computer bug" after finding a moth stuck inside Harvard's Mark II computer in 1947 (which in turn led to the term "debug," meaning solving problems in computer code). She did the foundational work that led to the COBOL programming language, used in mission-critical computing systems for decades (including today). She worked in World War II using very early computers to help end the war. When she retired from the U.S. Navy at age 79, she was the oldest active-duty commissioned officer in the service. Hopper, who was born on this day in 1906, is a hero of computing and a brilliant role model, but not many people know her story.

In this short documentary from FiveThirtyEight, directed by Gillian Jacobs, we learned about Grace Hopper from several biographers, archival photographs, and footage of her speaking in her later years. If you've never heard of Grace Hopper, or you're even vaguely interested in the history of computing or women in computing, this is a must-watch:

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