Have you ever looked at something through a magnifying glass? Have you ever wondered what a butterfly’s wing, an ant’s jaws, or a blade of grass would look like if you were the size of a bug and could see it really close up? Even though most magnifying glasses don’t make things look that much bigger, you can see a lot more detail. You can see the tiny veins on a maple leaf, or maybe the little feathery bits of a moth’s antennae. But if you could magnify things by 50 or 100, or 200 times–far more than a magnifying glass can–you’d see even more detail. You might even see individual cells, the smallest parts of living things.
In the 17th century, people were just starting to make tools that could magnify things more than typical magnifying glasses. Galileo made telescopes to peer out at the stars and planets, magnifying far-off things to make them look a little closer. Other scientists began making microscopes, which looked a lot like miniature telescopes and made tiny things look bigger. But these early microscopes weren’t very strong. They only made objects look about 20 or 30 times bigger. But Antony van Leeuwenhoek, a cloth merchant from Holland with little formal education, would change all of that.
Antony was born in Delft in 1632, to an ordinary, middle-class family. His father was probably a basketmaker. Delft itself would have been an exciting place to grow up though: It was a flourishing market town. It produced a famous style of blue-glazed pottery and was a stop for trading ships due to its canals.
Antony got involved in commerce early. He raised silkworms and sold them to silk merchants who would transform their cocoons into delicate, luxurious cloth. Antony’s family was comfortable, but not enough to give him the education it would take to become a scientist. Being from a family of tradespeople, he was sent to Amsterdam at 16 to learn his own trade or a job that he would spend his life working at. He became an apprentice, or trainee, to a draper, and learned about the business of making and selling cloth. He became a master of this trade, then moved back to Delft to open his own shop.
Being a draper, Antony had to use magnifying glasses as part of his job. He used them to examine cloth samples before he bought them. He would peer through one to carefully count the threads in a section of cloth, noting whether they were straight and smooth, before deciding what he would pay a trader, and how much he could charge customers for it in his shop. Maybe as he was hunched over scrutinizing cloth, he sometimes thought back to his silkworms and wondered what their tiny jaws or feet would look like under that same magnifying glass.
But as a young man with a business and growing family, Antony probably didn’t have much time to look at bugs under his magnifying glass. He worked hard at his shop, and became involved in his community, serving in several jobs in the city government. But, he did start to experiment with making better lenses to help him see the cloth, and as time went on, his curiosity about the world he could see under those magnifying glasses only grew.
Around 1668, Antony had the chance to visit London, England. It was probably while there, that he first saw a book by an English scientist, Robert Hooke called Micrographia. Hooke worked with microscopes. Even though they weren’t very powerful and could be blurry, Hooke had managed to observe and sketch hundreds of fascinating objects– molds; moth wings; plant roots; and the sharp, stinging points of nettles.
Antony was captivated. He wondered what else he might see if he looked. He also wondered whether he could make his own microscope that would work even better. After all, he had experience making lenses, the most important part of a microscope, for his cloth trading business. But what Antony would create turned out to be capable of much more powerful magnification than anything else ever built.
After many years, Antony earned enough money from his cloth trade, inheritance, and city jobs to close his shop. He used his new free time to practice his new hobbies: creating lenses and building microscopes. He ground some of his lenses down from pieces of glass using sand. Others he made by melting glass and using a tiny, red-hot droplet which he worked into a nearly-round shape as it cooled. The lenses made from blown, melted glass were especially clear and probably allowed Antony to make some of his most amazing discoveries about the microscopic world. Some were almost just tiny beads, and others were shaped like discs that curved outward on both sides, like a lentil. If you have a magnifying glass at home, the glass in it will also have this lentil shape if you run your fingers over it.
Not only were Antony’s lenses different from previous microscope lenses, but his microscope’s designs were also completely different too. Instead of making a microscope that looked like a smaller telescope, with a lens at each end, Antony would sandwich one lens between two metal plates, each with a small hole, just a bit smaller than the lens itself, to hold it in place. A screw was mounted onto plates to adjust how far the sample (the thing being observed) was from the lens. Antony’s microscopes were small all over: most measured one inch by two inches! Instead of sitting on a table, like other microscopes of the time, you would hold one right up to your eye to see the sample.
But even if they were small, Antony’s microscopes were revolutionary. The lenses were very clear and high quality. And where older microscopes magnified things about 20 to 30 times, Antony’s made objects appear about 200 times larger! Antony became obsessed with looking at things under his microscopes. He measured everything and drew detailed pictures. He looked at the jaws of bumblebees, wood, blood cells, lice eggs from his socks, and much more. He was constantly looking for specimens to study.
One day, Antony collected some water from a pond. It looked completely clear and fresh. But, even though nothing was visible when he looked at the water with his eyes, under the microscope he saw a world crowded with life, a multitude of tiny organisms swimming around. This was a stunning discovery. No one even suspected that living things might be swimming around in clean water! But because his microscopes were so powerful, Antony was able to make the invisible visible. He called these life forms “animalcules”, or “tiny animals” in Latin.
He also scraped the gunk off his own and his neighbors’ teeth, smearing it onto his microscopes. Antony took time each day to scrape his teeth clean, which was unusual for the time. He compared his tooth gunk to that of his neighbor, who rarely cleaned their teeth. He noticed far fewer animalcules hanging out in his own tooth goo than that of his less-hygienic neighbor.
Antony sent his drawings, measurements, and detailed descriptions to the Royal Society of London. The Society was a group of the most prominent scientists of the time. Robert Hooke, the author of Micrographia, was a member. Many in the Society doubted that Antony was telling the truth about his discoveries. They had never seen the kinds of things Antony described under their microscopes. Hooke was skeptical too, but he decided to try to observe similar samples for himself. After months of trying, Hooke was finally able to see some of the tiny beings that Antony had described. He presented the findings to the Royal Society, and they finally invited Antony to join the group. He never attended any meetings in person but did keep writing letters to the Society until his death fifty years later, detailing discovery after discovery.
As his reputation spread, many people visited Antony’s workshop to look through his microscopes. The Czar of Russia spent two hours observing his specimens! But Antony was secretive about how he made his microscopes and kept the best ones hidden away from visitors. He never wanted to teach others just how he made his high-quality lenses either because he felt it would take too much time away from his own observations. Unfortunately, only a few of his microscopes survived, and others would take years to reconstruct the knowledge of how he built them
Even so, Antony’s observations revealed a whole new world of life that had been invisible up till then. Eventually, others would discover that some of the denizens of this invisible world caused diseases. Nineteenth-century scientists like Louis Pasteur and Alfred Koch would make these connections over 200 years later. In the 20th century, scientists would delve even further into the invisible, studying the internal machinery inside animal and plant cells and bacteria, using microscopes even more powerful than Antony could have imagined or devised. We also came to understand that not all members of this invisible world are responsible for diseases–many don’t bother us at all, and some even help us.
Antony van Leeuwenhoek made his microscopes and observations with very little formal education or support. He didn’t speak the languages used by scholars of the day–English, Latin, and Greek. He only spoke Dutch. But he made over 500 of his tiny microscopes and spent nearly every day for fifty years observing. He looked at anything and everything under his microscope. He didn’t need a reason, his curiosity just drove him to look.
What are you curious about? How can you learn more about it? Whether you read about it in books, observe it under a microscope, or set up an experiment, follow that curiosity! You never know what you’ll find.
Sources
https://www.bbc.co.uk/history/historic_figures/van_leeuwenhoek_antonie.shtml
https://micro.magnet.fsu.edu/primer/museum/hooke.html
https://ucmp.berkeley.edu/history/leeuwenhoek.html
Curtis, Robert H. (1993) Great Lives: Medicine. Macmillan, New York.