The origins of microscopy

Van Leeuwenhoek’s secret uncovered only recently...
21 February 2022

Interview with 

Sietske Fransen, Max Planck Institute for Art History & Keith Moore, Royal Society


Microscope Silhouette


We are going to be getting up close and personal with our own cells by exploring microscopy. And not only are we looking down the microscope, we are getting inside our specimens. Anoushka Handa spent the week walking around inside a human immune cell. It started 350 years ago. Sietske Fransen from the Max Planck Institute for Art History and Keith Moore from the Royal Society gave an insight into the man who had the first glimpses of life under the microscope, Anthony Van Leeuwenhoek...

Anoushka - Not only are we looking down the microscope, we're getting inside our own specimens.

Julia - You what?!

Anoushka - I've spent the week walking around inside a human immune cell.

Julia - I'm sorry that doesn't really help me. What are you on about? How?

Anoushka - It's been a bit of a journey and it started around 350 years ago. Sietske Fransen from the Max Planck Institute for Art History and Keith Moore from the Royal Society, gave me an insight into the man who had the first glimpses of life under the microscope, Anthony Van Leeuwenhoek.

Julia - I am very excited to hear about what he saw.

Sietske - There is a possible link with his profession. He was a cloth merchant. And cloths merchants used magnifying glasses to look at the cloth they were buying and selling because they could count the number of threads per square centimetre. That would say something about the quality of the cloth that they were trying to buy and sell. Maybe his interest came out of his day job, but at the same time, he was definitely doing science for what he would have described as doing science. And I'm saying that because he was really keen on writing his experiences or describing his experiences to the fellows of the Royal Society. And he wanted to be part of that crowd. People often say about Anthony Van Leeuwenhoek that he was secretive and he was secretive about one thing. And that is how he made his microscopes.

Anoushka - What was his microscope? How did he make it? What does it look like? How big is it?

Sietske - Nothing you would think of if you now think of your binocular microscope that you might have used at school. It's a very tiny instrument. It's about four or five centimetres in height. There are two metal plates in between which there is a small glass ball, which is the lens.

Anoushka - What kind of specimens did he look at?

Sietske - He looked at everything. So the first experiments that Leeuwenhoek is sending to the Royal Society are of a bee or of a louse. But very soon after he also starts to look at bodily fluids. So blood, sperm, saliva, he takes a lot of his things that are immediately on him or around him because he also looks at his own hair. All tiny things that he can put on that microscope.

Anoushka - When were they found? And have they been replicated since?

Sietske - We know that he sent whole sets of them to the Royal society and they've gone missing. The ones that have been found, some of them are already no longer seen as original microscopes and others have more recently been discovered. It's only discovered in the past few years how we actually made the lenses because of course, of the few microscopes we have have left, they're made with dropped glass. So, it's a little glass ball and the melting of glass and making a small drop is not hard. However, Leeuwenhoek was grinding them. He was a showman. I think also he saw it as a case of pride to be accepted by people like the fellows of the Royal Society.

Anoushka - What better way to understand Leeuwenhoek than to go to the Royal Society to see if I could have a look at these letters myself. I met up with Keith Moore who brought out four massive volumes of letters.

Keith - We can start at the very beginning here. There are drawings in the margins sometimes. So they're all coming from Delft. You can see the date on this one very clearly 7th April 1674. So this is the beginning of his series of researches sent to the Royal Society. What you get here are not just textual descriptions of what's happening, but also drawings. And he sent them over so that the observation could be seen as a visual resources in addition to being a textual one. And he also at certain point sent over packets of specimens, so that fellows of the Royal Society in their meetings could try and replicate the observation.

Anoushka - I've heard that he's looked at his own blood, semen, and sweat. Did he send those over?

Keith - No, happily not. I mean, he used his own body as a means of finding things to look at under the microscope. It must have been an absolutely wonderful time to be a scientist. This was because almost whatever you looked at under the microscope would be something new, something that no one had seen before and therefore Leeuwenhoek and his whole generation of microscopists were really pushing a new frontier.

Anoushka - So let's have a look at some of the images. This is dated...

Keith - January 1680 from Delft and it's to Robert Hook because by this time he's the secretary of the Royal Society and Leeuwenhoek is sending over very beautiful drawings to him. He wouldn't have done them himself, so Leeuwenhoek, would have handed his microscope over to an artist and it was quite collaborative.

Anoushka - What else are we seeing on this page here? So we can see a centipede...

Keith - That's right. Centipede or a milipede. You've got a fly here, got some grubs as there are. Leeuwenhoek's letters very often send multiple observations. He'll incorporates several different things into a letter.

Anoushka - So he's just going out into the world with this microscope in his pocket.

Keith - That's absolutely right. What is this thing made of? How does it work? What's it in terms of living creatures? What are the structures that make up this thing?

Anoushka - Can I have a flick through these books?

Keith - You can. Leeuwenhoek did develop other kinds of microscope, things like water microscopes. So he could look at things that were living.

Anoushka - These are seeing things on around a millimeter scale?

Keith - It depended on the type of microscope Leeuwenhoek was using. He manufactured different types of lenses depending upon what he wanted to look at. So there are very high resolution instruments. If you're getting down to looking at bacteria, that is high resolution. But for most workaday things, he could use a lesser resolution. So he was using microscopes that were designed and made for a particular purpose.

Anoushka - Is that a whole fish?

Keith - That's a whole fish. So that's presumably quite a small one, but he's looking at some of the structural elements as well. There we go. One rats testicle.

Anoushka - But it looks like there's loads of swells here and waves. I'm guessing that's just the tissue?

Keith - That's right. So you're just seeing tissue floating in liquid there.

Anoushka - So Leeuwenhoek goes from looking at a whole fish all the way down to bacteria. Not only has he crafted lenses for different kinds of microscopy, but he can look through that whole range.

Keith - He was a remarkable individual and not just a good scientist and observer, but a remarkable art designer for being able to construct things like that, in order to observe such a range of material,

Julia - Sounds like you had an absolute ball!

Anoushka - It was teste-ing that's for sure.


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