Antonie van Leeuwenhoek

Antonie van Leeuwenhoek, a Delft cloth merchant, ground tiny single lenses and built hundreds of simple microscopes from the 1670s, some magnifying around 270 times. With them he became the first to describe bacteria, protozoa and sperm cells, reporting his findings in letters to the Royal Society. His instruments opened microbiology, though he kept his best lens-making methods secret.