Breaking Down Science, Step by Step

People often credit Anton van Leeuwenhoek as the father of microbiology. If this is the case, then he was a deadbeat dad, and microbiology is his bastard. This story begins with Robert Hooke, the quintessential the "also ran" of history, always coming close to the biggest discoveries of his time, but never quite making it. His role in this tale is no different.

Robert Hooke was the man who first popularised the microscope. In 1665, he published the "Micrographia". Within it he drew exquisite images of everything he had placed under a microscope. The public were enchanted by the patterns within cork plants, the structure of they eye of a fly, and the first detailed image of a flea. However, within five years of its publication, many of its findings were overshadowed by the work of an extremely talented Dutchman.


This Dutchman was Anton van Leeuwenhoek. He'd developed a keen interest in Microscopy during his time working as a garment seller, using microscopes to inspect the quality of the weave. In his workshop he quietly developed some of the most advanced microscopes of his era. With it He could see organisms too small to be visible to the naked eye. Organisms that no one else could see. He had discovered the microbes.

Like Hooke before him, he stunned the world with his intricate drawings of these tiny creatures. He discovered single celled organisms. His regard spread throughout Europe. His biggest fan may have been Robert Hooke himself ! He certainly supported Leeuwenhoeks work, and if anything was frustrated that there weren't more people like him.

Hooke lamented that the entire field of microscopy had been "Reduced to a single Votary, which is Mr Leeuwenhoek". Whilst the world was filling with astronomers, mathematicians and naturalists, there was only one person who was looking into the tiny world of single celled organisms.

But the question is, why was Anton van Leeuwenhoek the only microscopist left in the world ?


Hooke believed that it was the lack "of the inquisitive genius of the present age". i.e. no-one was interested in the subject. I think that there were somewhat justifiable reasons why people weren't interested in microscopy. Those had something to do with Leeuwenhoek himself.

Leeuwenhoek was intensely defensive of his discoveries. He always feared that some other may come along to take the credit. It was a fear that Robert Hooke would feel was very justified. Hooke believed himself to have come up with the idea for gravity, only to have it cruelly purloined by Isaac Newton*.


Leeuwenhoek kept his methods secret, apprenticed no students, and hid the microscopes he had used to make his discoveries. But as a result of his extreme defensiveness, no-one was willing to take up microbiology. They couldn't compete with him, and they certainly couldn't collaborate. It is probably no coincidence that the popularity of microscopes increased significantly after his death in 1723.


Whilst microscopes could be found in some places, they were primarily based on Hooke's design than Leeuwenhoek. So they weren't exactly of the highest standard.

They produced distorted images, due in part to a process known as "chromatic aberration". No-one knew how Leeuwenhoek got around these problems, and it would be a long time before anyone would create microscopes of comparable power. For over a hundred years, microscopy would effectively be dead. It would eventually be resuscitated. Not by microbiologists, but by astronomers. There was a burgeoning movement with amateur astronomy, and as a result there was a huge demand for ever better telescopes to produce better images.


Lenses work by re-directing light into a focal point by taking advantage of light slowing down when it enters glass. Using shaped glass allows you to bend light, and focus it to magnify an image.


Each part of the wavefront entering the lens is slowed down, but because of the shape of the lens, they are all slowed down for different lengths of time, causing them to be distorted. This means that wavefronts coming out of the convex glass end up focused on one point.

This effect is the basis for telescopes, spectacles and your eye's ability to read the words I've just typed.


Here is the problem. Any optical material can split different wavelengths of light. The various wavelengths of light slow down to different speeds, causing them to separate. This is what happens when we pass light through a prism, or when it goes through the raindrops to form a rainbow. It also causes chromatic aberration.


Chromatic aberration causes multiple images of different colours to have different focal points. This results in blurry and miscoloured images. Leeuwenhoek's microscopes had sidestepped these problems by being incredibly small. Since each light wave had only a small distance to travel, they wouldn't get far enough away from eachother to produce a distorted image.

It was an amateur optician named Chester Moores Hall who eventually solved the problem. The answer came to him as a result of his studies of the human eye. He noticed that the human eye itself had a spherical lens, so why wasn't human sight blighted with chromatic aberrations ?


He hypothesised that the jelly like vitreous humour in the eye held the answer. Somehow, the vitreous humour cancelled out the aberrations caused by the lens. He decided to use a similar method to compensate for the chromatic aberrations. He knew that some glasses would separate light in the opposite way to others. So if he used a type of glass that would naturally bend light the opposite way to the lens, he could use it to cancel out the splitting of light caused by chromatic aberration. He decided to use flint glass to form a cover over the lens, and theoretically correct for any aberration.


He had one big problem. He couldn't grind his own lenses. He needed to get someone to make his special lenses, but he didn't want any of them to figure out that he had solved chromatic aberration. Like Leeuwenhoek before him, he wanted to keep his discovery a secret.

He used different lens-makers to make each part of his new invention separately. One would make the objective lens, and the other would make the corrective cover for it.


But Chester Moores Hall fell victim to an unfortunate coincidence. Neither of these lens makers could make the parts he requested, and both of them decided to subcontract the work onto the same man. A man named George Bass. When he constructed both of the primary parts for the lenses, he literally put the pieces together, and figured out what Chester Moores Hall had done.

George Bass mentioned this discovery to another optician, John Dollond, who had also been struggling with the same problem. Dollond immediately patented this discovery, and started selling corrective lenses that accounted for chromatic aberration.


It was his son, Peter Dollond, who decided to fully enforce those patents. By this time, many other opticians around London were using chromatically corrected lens. Peter Dollond managed to use his fathers patent to try to run them out of business. In the subsequent legal proceedings, Dollond's competitors believed they had an ace in the hole. They called Chester Moores Hall to the stand, who confirmed that he was indeed the true inventor of the achromatic lens, giving them the right to dispute the patent.

The problem was that Chester Moores Hall kept it all a secret, which became a major sticking point for the judge. The Judge ruled in favour of Dollond, because Dollond had tried to use the invention to benefit others.


It was a Dutch instrument maker named Jan van Deijl who had managed apply achromatic lenses to microscopes. But he wanted to get them absolutely right, and spent such a long time perfecting them that the work had to be passed down to his son Harmanus, who would eventually publish that work and set up a company to start selling microscopes. They suddenly became popular again, and scientists like Giovanni Amici and Joseph Jackson Lister* made further improvements to this design. It was the work of these people that successfully resuscitated Microscopy.

Soon these instruments were in high demand, with microscope manufacturers popping up across Europe, and then across America. They became the essential tools for naturalists and physicians, and microscopy became the forefront of important research during this era.


How much earlier would those discoveries have been made if Leeuwenhoek had shared his methods ? We can only speculate. Perhaps I may be being hard on the man for simply adhering to the standards of his era. But calling him the "Father of Microbiology" implies that "Microbiology" owes him its existence.

Think about this. In a world without Leeuwenhoek, what would be different ? Ingenious lens crafters would have still made improvements to Robert Hooke's microscope, using discoveries made by astronomers. The Germ Theory of disease would still have come about in the 18th century. In practical terms, Microbiology would be no different without him.


References and Further Reading

Cassedy J.H. (1976). The Microscope in American Medical Science, 1840-1860, Isis, 67 (1) 76. DOI: 10.1086/351546


Dobell, Clifford (1932). Antony van Leeuwenhoek and His "Little Animals": being some account of the father of protozoology and bacteriology and his multifarious discoveries in these disciplines. New York: Harcourt, Brace and Company.

Department of the History of Science (Harvard) Description of Harmanus Van Deijl's compound microscope


Nineteenth-century Scientific Instruments by Gerard L'Estrange Turner

Peter Dollonds answers Jesse Ramsden -…


* The impression I get from what I've read is that Robert Hooke, like many scientists of his era had come up with the rough idea that celestial bodies attract each other, and that attraction dissipates with distance, but it was Newton who actually went ahead and created a mathematical model with a series of quantifiable laws to explain these phenomena. Which is why (IMHO) Newton wins that particular argument.


** Not to be confused with his son, Joseph Lister, the pioneer of antisepsis.

Image credits

Top image- Robert Hookes Flea

Lens Images- Created for an earlier version of this article.

The first draft of this article was published here-…

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