The simple microscope can be traced existent at around 1700 in Delft, Netherlands, having utilized by a draper named Leeuwenhoek. His name, as it has come down to us, is Antony van Leeuwenhoek, but he was christened ‘Thonis’, and acquired the ‘van’ as an affectation in 1685 when he was fifty-two. He had a normal secondary education, was apprenticed to a draper in Amsterdam, and lived for his adult years in the pleasant and quiet city of Delft , much of which has changed relatively little since Leeuwenhoek’s time.

Oh his own, and in his spare time, he founded the science of microbiology. It was Leeuwenhoek who drew cells and, with them, the cell nucleus, it was he who documented spermatozoa; it was Leeuwenhoek who discovered the microbe world and first observed bacteria. The kind of microscope he used was hand-made, sometimes being fashioned from metals he refined himself and then beat into shape.

The lenses he made himself from fragments of glass. Well, this very microscope we are considering here is actually in Utrecht, at the University Museum. It has been brought from a locked safe, for the ‘Leeuwenhoek microscope’ in the display cabinet is only a replica, the original is too precious by far to leave lying in a glass case and carefully tipped from its little cardboard box.

There is a single lens set into the metal plates of the microscope body. This bead of glass has a magnification of 266 times, at which rate a bluebottle fly would be a metre in length and even a smaller-than-average bacterium would be clearly visible as a round dot the size of this full stop. The moving bacteria of ponds, and the swimming organisms that live between our teeth, all show up with clarity.

Leeuwenhoek used a series of simple screws to move the specimen across the field of view, and to focus its image, and yet this simple little instrument is still capable today of magnifying as well as you would need for most modern scientific purposes. The highest magnification that can be obtained with a modern microscope is around a thousand times and here we have a little hand-made microscope some three centuries old that can itself reach to one-quarter of that.