Why We Have Different Types of Screws

iStock/teerawut111
iStock/teerawut111

If you've ever mistakenly grabbed the Phillips head screwdriver when you needed a flat head, you've probably asked yourself why there are different types of screws. Let's start at the beginning.

The screwdriver, originally called a screwturner or turnscrew, entered the world inconspicuously and kept a very low profile until its 300th birthday. Historians believe it was invented in Germany, but aren't sure exactly when. The Medieval Housebook of Wolfegg Castle, the oldest known written reference to the tool, has a hazy publishing date somewhere between 1475 and 1490. Considering the invention likely predates the book by at least a few years, the mid to late 15th century is about as exact a birthday as it gets. For about 300 years, the persistent presence of screws is the only solid evidence that screwdrivers even existed. Then, suddenly, documentation of screwdrivers exploded across Europe, particularly in France.

Early screwdrivers had pear-shaped handles and were made for slotted screws. Metal screws as we know them today have been in use since at least the 15th century for cabinetry work and to secure plates on jousting armor. Before that, wooden screws were used in wine and olive oil presses as far back as the 1st - 3rd century BC (how they turned them for so long without a screwdriver, I haven’t been able to figure out).

These early metal screws were prohibitively expensive. It wasn’t until several advances in screw making – among them, Jesse Ramsden and Henry Maudslay's screw-cutting lathes and David Wilkinson’s and Job and William Wyatt’s mass production of screws on assembly line-like systems – occurred around the beginning of the First Industrial Revolution that the screw became easy enough to produce to become popular and widespread. This increase in popularity, of course, led to the refinement and diversification of the screwdriver. The tool took on many different shapes and sizes, though for a long time every version was still for flat slotted screws, which were the only type around.

Better Heads

This changed in 1908, when Canadian P.L. Robertson patented the “first recess-drive type fastener practical for production usage,” a recessed square-drive screw that bears his name. Robertson screws became a standard in Canada and gained a buzz in the U.S. when the Ford Motor Company, one of Robertson's first customers, used over seven hundred of them on each Model T. The square-drive head on Robertson screws had an advantage over slot heads because the driver was relatively easy to get situated on the head and stayed put during installation once it was there. A screw like Robertson’s became crucial as American manufacturers moved increasingly toward mass production methods. The time it took to align the driver with the slot, multiplied across thousands of workers in a factory and across hundreds, if not thousands, of screws per worker per day, became a significant loss of time and money. Additionally, the automated screwdrivers used on assembly lines often slipped out of the screws’ slots and into whatever component was being assembled or stripped the screw once it was driven all the way. [Image credit: Saforrest]

The American automobile industry was especially in need of a screws screw that could stand up to the torque of their automated drivers and be fitted and tightened quickly, but a bad break in Robertson’s past doomed him just when his invention was needed most. Dealing with dishonest parties while licensing his screw in England, Robertson wound up losing the rights to his invention and had to spend a small fortune to buy them back. When Ford, wanting to protect his assembly advantage (the screws saved his workers two hours of assembly time per vehicle), asked for a licensing agreement from Robertson so that he could manufacture and control the distribution of the screws, Robertson turned him down and he refused to allow anyone to make the screws under license. After their run on the Model T, Ford had to limit the use of the screws to his Canadian division and the widespread adoption of the Robertson screw in the U.S. fizzled and failed.

Enter Portland, Oregon-based businessman Henry F. Phillips and the patent for a screw with a deep X-shaped slot, which he had purchased from friend and inventor J.P. Thompson. Phillips refined the design of the fastener, today known as a Phillips screw, for automated screwdrivers. The X-shape of the slot and pointed tip of the Phillips head screwdriver made the driver self-centering and unlikely to slip out when it wasn’t supposed to. The recessed slot was shallow enough, though, that the driver did pop out when the screw was fully tightened, which prevented over-torquing and damage to the screw, the driver and the product being assembled.

The American Screw Company began mass-producing Phillips’ design. A successful trial on the 1936 Cadillac helped it proliferate through the U.S. auto industry. By 1940, 85% of the screw manufacturing companies in the U.S. had a license to produce the Phillips screw design. Usage spread from the auto manufacturers as the Phillips drive system was used during the Second World War on many wartime products and vehicles. Though originally meant for automated, industrial applications, Phillips screws and handheld screwdrivers found their way into the toolboxes of handy men and women across the country by the turn middle of the century. [Image credit: U.S Patent and Trademark Office.]

Other Ways the World Turns

Most anyone who’s had to fix anything at home or put together an IKEA couch has heard of slotted and Phillips screws and maybe even hex sockets. The world of screws is vast, though, and plenty of other types of screw heads and drives exist, like the Mortorq, the Pozidriv and the Bristol. You can take a crash course in the different types of screws here, and if you want a more in-depth history of screws and drivers, check out Witold Rybczynski’s One Good Turn: A Natural History of the Screwdriver and the Screw.

A Lost Japanese Village Has Been Uncovered in the British Columbia Wilderness

Ferenc Cegledi/iStock via Getty Images
Ferenc Cegledi/iStock via Getty Images

In 2004, a retired forester reached out to Capilano University archaeology professor Bob Muckle about investigating what looked like the remnants of an old logging camp in the forests of British Columbia, Canada. North Shore News reports that each spring for the next 14 years, Muckle took his students there to help him excavate what he now believes was a sort-of-secret Japanese settlement.

The site is located on the Lower Seymour Conservation Reserve, about 12 miles northeast of Vancouver. It’s approximately the size of a football field and contains the remains of more than a dozen cabins, a bathhouse, a road made of cedar planks, and a cedar platform that may have been a shrine. Muckle and his students have also unearthed more than 1000 items, including sake and beer bottles from Japan, teapots, game pieces, medicine bottles, clocks, pocket watches, clothing buttons, coins, and hoards of ceramics.

Japanese businessman Eikichi Kagetsu secured logging rights to the area near the camp around 1918, so it’s likely that the settlers were originally loggers and their families. Though the trees were cleared out by 1924 and Kagetsu continued his business ventures on Vancouver Island, there's evidence to suggest that some members of the logging community didn't leave right away.

Muckle believes that at least some of the 40 to 50 camp inhabitants chose to remain there, protected from rising racism in Canadian society, until 1942, when the Canadian government started moving Japanese immigrants to internment camps in the wake of the outbreak of World War II.

Muckle thinks the residents must have evacuated in a hurry since they left so many precious and personal items behind. “When people leave, usually they take all the good stuff with them,” he told North Shore News. His team even uncovered parts of an Eastman Kodak Bulls-Eye camera, a house key, and an expensive cook stove that someone had hidden behind a stump on the edge of the village. “They were probably smart enough to realize people might loot the site,” he added.

According to Smithsonian.com, Japanese immigrants had been victims of racism and discrimination in Canada since the first wave of immigration from Japan in 1877. They were generally met with hostility across the country, and kept from voting, entering the civil service, and working in law and other professions. Anti-Japan sentiment dramatically worsened after the bombing of Pearl Harbor in 1941, and The Canadian Encyclopedia estimates that more than 90 percent of Japanese Canadians—many of them citizens by birth—were displaced during the war.

To Muckle, this all contributes to the likelihood that villagers would have chosen to stay insulated by the forest for as long as they could. “The impression that I get, generally speaking, is it would have been a nice life for these people,” he said. It wouldn't be the first time a remote, wild area served as a refuge for a persecuted community—farther south and east, escaped enslaved people settled in the swamplands bordering North Carolina and Virginia for the century leading up to the Civil War.

While Muckle believes people stayed in the Canadian camp until the 1940s, it's hard to prove—there are no records for the inhabitants of the camp or where they might have gone. If there’s evidence in the village that can prove residents did stay until the 1940s, it will soon fall to other curious archaeologists to find it: Muckle thinks this will be his last season at the site.

Or, maybe the smoking gun will be discovered by someone who isn’t an archaeologist at all. Here are 10 times ordinary people (and one badger) unearthed amazing archaeological finds.

[h/t Smithsonian.com]

Caught in the Devil's Backbone: The Mysterious Death of Meriwether Lewis

Photos.com/iStock via Getty Images Plus
Photos.com/iStock via Getty Images Plus

Priscilla Grinder wasn’t sure what to make of her new guest's odd behavior. When she'd welcomed him to the inn she ran with her husband, Robert, that evening of October 10, 1809, he'd come with packhorses and a request to stay the night. On the surface, he was merely one of many to make the trek along the Natchez Trace, a 450-mile path that connected Natchez, Mississippi, with Nashville, Tennessee. The trip could take up to four weeks, and weary travelers often found shelter in one of the many inns along the way. It was here at Grinder’s Stand, near Hohenwald, Tennessee, where this particular traveler had stopped to get some rest.

Priscilla watched as the man moved about in an erratic manner. When servants who had been traveling with him arrived, the guest ordered them to the stables [PDF]. Then he began pacing. He would walk up to Priscilla, and then quickly turn around. At supper, he took only a few spoonfuls of his meal before launching into what she would later describe as a “violent” verbal tirade directed at himself. He then retired to his room, where his footsteps echoed across the hardwood. Priscilla and her children—Robert was not at home—retired to nearby quarters, disconnected from main cabin but within earshot.

Late into the night, Priscilla heard what sounded like a pistol being fired. And then another. She heard the man cry out, “O Lord!” As she peered out of spaces between the wooden walls, he appeared, bleeding and rambling. He begged for water and for Priscilla to “heal” his wounds.

Priscilla was so shaken by the sight of the wounded guest, not to mention his odd behavior earlier, that she did something nearly unthinkable: She ignored him. His pleas for help went unanswered. When the servants arrived from the stables early the next morning, the guest begged them to kill him. He was missing part of his forehead and, according to some accounts, had slashed at himself with a razor.

He died at sunrise.

And that was how Meriwether Lewis, aged 35 and once co-captain of the famed Lewis and Clark expedition, met his untimely end. For the next 210 years, scholars, his family, and forensic analysts would comb over his life—and attempt to analyze his remains—searching for an evasive truth. Had Lewis turned his pistol on himself? Or had someone at Grinder’s Stand murdered him?

 

With the Louisiana Purchase, when the United States bought 828,000 miles of French territory in 1803, the country nearly doubled in size. President Thomas Jefferson was determined to map the new acquisition, forge relationships with Native American tribes, explore the flora and fauna of the region, and, most importantly, find an all-water route to the Pacific for trade purposes. Jefferson appointed Meriwether Lewis—his protégé, one-time secretary, and an Army captain—to lead the expedition.

Between 1804 and 1806, Lewis, his co-captain William Clark, and their team traversed 8000 miles, enduring bad weather, treacherous terrain, hunger, disease, and, at times, hostile Native Americans. He and Clark returned from their expedition to St. Louis, Missouri, as heroes in September 1806.

A postage stamp honoring explorers Meriwether Lewis and William Clark is pictured
iStock.com/traveler1116

The rewards for enduring such an arduous trip were numerous. Jefferson gave Lewis double pay for the journey and 1600 acres of land. Lewis was also named governor of the Territory of Upper Louisiana.

By rights, Lewis should have settled into a comfortable post-expedition life. But it was not to be. Scholars have suggested that despite the plaudits he was receiving, Lewis might have been somewhat disappointed with the expedition. For one thing, Lewis and Clark had not found the all-water route—the fabled Northwest Passage—to the Pacific. For another, the trading posts they had helped set up were faltering. The government had also complicated matters by asking for additional documentation and evidence that some of the filed expenses were necessary. If they weren’t, Lewis might have had to pay for them himself, which would have drained him financially.

Lewis was also prone to dark moods, a gloom that Jefferson noticed throughout their long friendship. It could have been depression, exacerbated by Lewis’s tendency to drink alcohol to excess. Based on his symptoms, scholars have also suggested malaria or syphilis may have been attacking both his body and his mind: Lewis himself wrote in a journal in November 1803 that he had been seized with a "violent ague," ague being the term at the time for malaria, a parasitic disease transmitted by mosquitoes that was not then treatable by antibiotics. Lewis also made several moves that support the idea of a morose state of mind, arranging for his possessions to be disbursed in the event of his death and preparing a will.

On a boat headed for Fort Pickering in September 1809, a number of military officials reported that Lewis was obviously distraught and had made two attempts to take his own life. It’s not clear how he tried to do it, but the prevailing belief was that Lewis was in a state of deep despondency that appeared to some as a mental illness. Captain Gilbert Russell, who was in charge of Fort Pickering, would later state that he ordered Lewis detained until he regained his composure. "His condition rendered it necessary that he should be stoped until he would recover which I done [sic]," Russell wrote. Lewis, he added, exhibited "mental derangement."

Lewis traveled on, following the Natchez Trace, and headed for Washington, where he intended to answer to questions concerning his expedition expenses. That’s when he stopped off at Grinder’s Stand.

It would be his last night alive.

James Neelly, a federal agent also on the Natchez Trace trail, had traveled part of the way with Lewis and had witnessed the explorer's odd behavior. The two had split up the morning of October 10, when Neelly remained behind to pursue two escaped horses.

Neelly came upon the grisly scene the day after Lewis's death. He buried the explorer near the inn and wrote to Jefferson that the death was a suicide. Owing to Lewis's recent behavior, it was an apparently easy assessment to make, and there was no autopsy or further investigation. But not all of the facts supported that conclusion.

 

According to the servants who discovered him, Lewis had purportedly shot himself in the head, a non-fatal wound that failed to penetrate his brain. Then he was believed to have turned the gun to his abdomen and fired again, the ammunition tearing through his torso and out near his backbone. But Lewis was a military man and an expert marksman. If he intended to kill himself, skeptics argue, a glancing shot against his head and another in his stomach seemed to be lousy choices. Surely, he would have had the sense to aim for his heart or to take a more measured aim toward his brain. Lewis's own mother expressed doubts; she believed he had been murdered.

The suspicion of foul play grew in 1848, almost 40 years after Lewis's death, when his body had to be partially exhumed in order for a monument to be erected at his burial site. The medical professionals who assisted in the exhumation reportedly made an offhand declaration: One of the bullet holes appeared to be in the back of his head, a strange spot for a self-inflicted gunshot. "It seems to be more probable that he died by the hands of an assassin," the exhumation committee concluded.

A plaque stands next to a monument at the burial site of explorer Meriwether Lewis in Hohenwald, Tennessee
Ron Gilbert, Flickr // CC BY-ND 2.0

That comment, which lacked documentation or further explanation, ignited a number of theories about how Lewis had really died. Some—like the idea Lewis had been carrying on with Priscilla Grinder and was discovered by her returning husband, or that the innkeeper murdered Lewis for his money and possessions—seemed fantastic. Others seemed somewhat plausible. Known as the “Devil’s Backbone,” the Natchez Trace was considered rough both geographically—it was made up of uneven terrain—and because of the bandits who lurked in the woods, ready to pounce on travelers carrying goods. Lewis had died on a path riddled with crime, and though nothing appeared to be missing, it was not inconceivable that an assailant could have fatally wounded him. At least, it seemed more likely than the idea that a competent soldier tried to kill himself by gruesomely shooting and slashing his own body.

Another theory, put forward by historian Kira Gale in two books, 2009's The Death of Meriwether Lewis: A Historic Crime Scene Investigation and 2015's Meriwether Lewis: The Assassination of an American Hero and the Silver Mines of Mexico, argues that Lewis was the target of a political assassination. As governor of the Louisiana Territory, he may have run afoul of a plot by General James Wilkinson (his predecessor as governor) to control lead mines south of St. Louis and invade Mexico to seize silver mines. Wilkinson was far from trustworthy, having sold American secrets to the Spanish empire and even warning Spain of the Lewis and Clark expedition and forthcoming American expansion. If he believed Lewis could expose his plans for the mines, he might have taken extreme measures to guarantee his silence.

"I propose the motive was to prevent Lewis from bringing information to Washington regarding crooked land deals involving Wilkinson and John Smith T, a mine operator in the lead mine district south of St. Louis," Gale wrote in 2015. "Wilkinson had a history of assassinating, or attempting to assassinate, people who were his rivals and possessed incriminating information that could jeopardize his career. Meriwether Lewis was a man 'of undaunted courage' who stood up to him." Gale also asserts that Wilkinson poisoned Anthony Wayne, commanding general of the U.S. Army, so second-in-command Wilkinson would climb in the ranks. Wayne died in 1796 following a bout of intense stomach pain, which Gale argues was really arsenic poisoning.

Priscilla Grinder herself added to the ambiguity around Lewis's death with her shifting recollections. She had told Neelly about Lewis's final hours. But roughly three decades later, when prompted by a schoolteacher for her memories of the night, she said three strange men had followed Lewis to the inn and that he had warned them off with his pistol. She also noted that she had seen John Pernier, Lewis's servant, wearing the clothes Lewis had arrived in. (Pernier would go on to become an unlikely but persistent suspect, having no obvious motive beyond simple theft. He died seven months after Lewis in an apparent suicide.)

A theory presented by Lewis historians Thomas C. Danisi and John Danisi and published in 2012 [PDF] attempted to reconcile Lewis’s reported depression with the unusual nature of his death. They pointed to Lewis’s longstanding “paroxysm of intermittent disease,” or the physical discomfort he experienced as a possible result of malaria or syphilis infection. Jefferson had taken note of his friend’s maladies, and described them in letters as a “hypochondriac affection.” Jefferson, using the language of his day, didn’t mean Lewis was having health anxiety—he meant Lewis had some kind of bodily discomfort, possibly involving his alcohol-saturated liver or spleen. The expedition, Jefferson wrote, had taken Lewis’s mind off the discomfort. Upon his return, his mind had the freedom to return to it.

In the throes of pain, illness, and frustration, it’s possible Lewis turned his weapons on himself without intending to take his own life. Instead, the Danisis argue, he wanted to quiet his ailing body. In an addled state, he might have even thought a wound could “cure” his affliction. That would explain why he targeted his abdomen and why, when the two shots failed to resolve his discomfort, he may have taken to slashing himself with a razor. Had Lewis wanted to die, why beg the innkeeper’s wife for water and attention? Why ask—or make a proclamation—about “healing” his wound?

 

Lewis is still buried in Hohenwald, Tennessee, in land that is now federally owned and part of the National Park Service. In 1996, George Washington Law University Professor James Starrs petitioned for the body to be exhumed in the hopes of examining Lewis's remains and possibly shedding light on his cause of death. Even close to 200 years later there might still be tell-tale clues on the body: Gunpowder residue could be tested to see if he was shot at close range or not. Fracture patterns in the skull could indicate the direction of the shot. Somehow, forensic analysis might be able to resolve what’s grown into a mystery enduring over two centuries.

So far, those attempts have not been successful. Starrs received no cooperation from the National Park Service, who told him it would set a bad precedent and that they have no interest in disrupting a burial site. The exhumation idea was also floated in 2009 by Lewis's descendants, but rejected by the Department of the Interior in 2010.

There’s no guarantee that any evidence exists that could prove exactly what happened to Lewis the night of October 11, 1809. Sick and tired, he could have taken his own life. He could have been trying to cure himself of a persistent pain. Or he could have been victimized by a bandit or bandits that simply disappeared back into the Natchez Trace. It’s a secret that Lewis took to his grave—where it’s likely to remain for a long time to come.

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