In August 2023 we were looking back at the great Dutch pioneer of microscopy, Antony van Leeuwenhoek, who died 300 years ago. When news was released of my discovering Leeuwenhoek’s original specimens, it did not take long for someone to realise that they had one of his microscopes at home. Later, two more appeared, within the space of a few months.

Then, in December 2023, a fourth emerged. This one was a silver microscope found during a house clearance in East Anglia. Through the kindness of Christie’s, the auction house chosen by the owner to handle its sale, I had it for a day at the Cavendish Laboratory of the Universirty of Cambridge, and this provided a unique opportunity to reveal the fine details of its construction.

Proof that this came from Leeuwenhoek’s hand lies in the fact that it is a near-twin of his previous work. And it could be no replica; the finest details showed it was hand-made in a pre-industrial era. Replica screws are cut with dies, often using an over-sized die to imitate antique techniques.

The thread of this little microscope had been made by rolling, not cutting; exactly the same way as the thread on a brass microscope (shown in Lab Bulletin in August 2023). Scores of individual frames were obtained with the Hitachi SEM at the Cavendish Laboratory, so I now have exquisitely detailed pictures of both the brass and silver microscopes made by Leeuwenhoek in the decades around 1690, each some 1.5 metres from end to end.

These are unprecedented, and offer a revolutionary insight into the origins of microscopy.