Penicillin was being mass-produced and advertised by 1944. That antibiotic mold turned out to be the fungus Penicillium, and over the next two decades, chemists purified it and developed the drug penicillin, which fights a huge number of bacterial infections in humans without harming the humans themselves. The sample had become contaminated with a mold, and everywhere the mold was, the bacteria was dead. In 1928, the Scottish scientist Alexander Fleming noticed a bacteria-filled Petri dish in his laboratory with its lid accidentally ajar. It's one of the most famous discovery stories in history.
The size of the axle was also a critical factor, as was its snugness inside the hole (not too tight, but not too loose, either).Īlexander Fleming pictured in his laboratory (Image credit: Bettmann / Contributor) "But then making it was also difficult." For instance, the holes at the center of the wheels and the ends of the fixed axles had to be nearly perfectly round and smooth, he said. "The stroke of brilliance was the wheel-and-axle concept," Anthony previously told Live Science. Check out our pick of the best health and fitness deals this Amazon Prime Day.The wheel itself wasn't the most difficult part of "inventing the wheel." When it came time to connect a non-moving platform to that rolling cylinder, things got tricky, according to David Anthony, a professor of anthropology at Hartwick College.
(Image credit: James Steidl via Shutterstock)īefore the invention of the wheel in 3500 B.C., humans were severely limited in how much stuff we could transport over land, and how far. Wheels were invented circa 3,500 B.C., and rapidly spread across the Eastern Hemisphere.
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