Antony van Leeuwenhoek 1632 - 1723 (Part 3) Leeuwenhoek did not invent the microscope (compound magnifying lenses were known 40 years before he was born), but he took it to new levels of power. He was probably acquainted with magnifying lenses used to investigate the textiles in his trade. His only trip to London (between marriages, in 1668) introduced him to the unseen natural world under the magnifying lens shown in Robert Hooke’s popular new book, Micrographia. We can only surmise what sparked his interest in microscopy that was in full bloom five years later; this book? His second wife or her intellectual friends? His own curiosity about nature? Somehow, he began grinding his own magnifying glasses, and perfecting a way to mount them and hold specimens in position for viewing. Crude by today’s standards, they were nevertheless far superior to those used by Hooke, Swammerdam, Malphighi and others, and were unsurpassed until the 19th century. (The electron microscope would have to wait 250 years.) The compound microscopes of his day suffered from chromatic aberration and were not useful much above 20x. Leeuwenhoek made tiny lenses not much bigger than a pinhead in his simple microscopes, but aided with excellent eyesight, he achieved magnifications as high as 270x and 1.4 micron resolution. He was now in position to peer into a world never before seen by human eyes. Other scientists of the day were content to magnify well-known objects like leaves and textiles. Leeuwenhoek wanted to see the invisible. By 1673, when he was finding exciting things with his microscope, a friend put him in touch with the Royal Society of London. Antony sent them drawings (made by a friend) of bee stings and mouthparts, a louse and a fungus. The eminent British scientists were at first skeptical of the claims by this untrained layman who only spoke Dutch. When in 1676 he described finding microorganisms in water that were so small that “ten thousand of these living creatures could scarce equal the bulk of a coarse sand grain,” the surprised Royal Society requested corroboration from other eyewitnesses, especially since Robert Hooke himself could not repeat them (until later, with a more powerful microscope). Several friends, including a pastor, and a notary public, sent affidavits that they also saw these things through Antony’s microscope. As Leeuwenhoek’s observations were found to be true and accurate, his reputation grew, and by 1680 this untrained layman was elected a fellow of the Royal Society. Though he would never revisit London or attend a meeting, the Dutch cloth merchant kept up a lively relationship with the British scientists for fifty years, sending them hundreds of letters with attached samples, some of which survive to this day in the Royal Society archives, along with a few of his hand-made microscopes; though out of hundreds he manufactured, only nine survive.
Posted on: Thu, 07 Nov 2013 18:02:17 +0000
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