Many textbooks begin their list of early microscopists with Leeuwenhoek, who published most of his discoveries in the Philosophical Transactions of the Royal Society of London. This volume is an anthology of many of those articles. Leeuwenhoek’s microscope had only a single, powerful lens. He positioned the specimen on a needle with an adjustable handle. His extraordinarily detailed views of insects, like the flea on the left, caused a sensation. His lens magnified around 270x.