Antony van Leeuwenhoek is one of the most well known figures in the history of microscopy. He is particularly known for two achievements: his single-lens microscopes, the best of which was able to resolve objects down to 1 micrometre (a thousandth of a millimetre), and being the first human to explore the microcosm - the world of single-cell organisms such as algae and bacteria. It is for the latter that he is often ascribed the sobriquet of ‘The Father of Microbiology’.
Van Leeuwenhoek was born into the burgeoning and learned Dutch Republic. Delft, his home city, was heavily involved in foreign trade through the Vereenigde Oost-Indische Compagnie (the Dutch East Indies Company) and it was through trade as a draper that van Leeuwenhoek primarily earned his living. He supplemented his trade with various roles in public office throughout his life, including as the official wine-gauger of Delft.
To my knowledge there isn’t much third party documentation of van Leeuwenhoek, his parents or either of his marriages and one surviving child, Maria. However, Lens on Leeuwenhoek includes a timeline of over 600 documented events relating to van Leeuwenhoek’s life, his family and Delft during his lifetime.
Much of what we know of van Leeuwenhoek’s scientific work comes from his self-published collections of letters. These letters, written in Dutch, were published in seven volumes and totalling 364 letters of which 285 include scientific notions. Nearly all these letters are dated and addressed to individuals or specific bodies, including many to the Royal Society.
A few of these letters were published, usually only in extracts, in English, Latin and French. These publications were few and far between and included publications such as Philosophical Transactions (the world’s first exclusively scientific journal).
Like many early scientists, van Leeuwenhoek was a broad, observer and questioner of the natural world: a natural philosopher. His letters include observations of grains and fruits, including the tropical coconut, pig brains, mouse tendons, sheep testicles and uteri, fish, hair and skin samples. and more. Many of these were supported by copper engravings of his observations also published with his letters.
As a curious, self-taught man, van Leeuwenhoek was not afraid of trying his hand at a new challenge. In one of his civil roles, as surveyor, he would have been well aware of telescopes and, as a draper, he would have used low magnification glasses for determining thread count. Van Leeuwenhoek learnt to make his own glass lenses and to grind and to smith his own metal parts. With these skills he went on to make at least 559 microscopes and no doubt more that didn’t work, broke or were lost. He averaged over one microscope a month over 60 years of designing and building them.
Van Leeuwenhoek is most known for his single-lens microscopes, of which he made at least 271, but he also constructed a variety of other microscope in other designs. His single-lens microscopes, of which eleven have survived, where constructed of from a convex-convex (or spherical) lens, to metal plates, a mount and several threaded components all riveted together, of which van Leeuwenhoek will have made all. The surviving microscopes are only in brass and silver but some microscopes would also have been made in gold.
The threaded components of van Leeuwenhoek’s microscope design allowed him to secure the mounted specimen and, one of the unique features of his design, control the position of the mount in three dimensions and rotationally.
The lenses he used in these microscopes were amazingly small, uniformly round and of clear enough glass that he was able to observe objects smaller than any person before him. He was the first to observe and describe single-cell organisms, including bacteria down to a micron in diameter.
Many of van Leeuwenhoek’s minuscule discoveries were described in his letters in the classic, observational style of the time. Obviously in Dutch, he often described these micro-organisms as ‘exceedingly small animals’. In a translation of his early letters this was translated as ‘animacules’, a word often associated with van Leeuwenhoek.
Van Leeuwenhoek’s jobs as cloth merchant and surveyor well prepared him for the new world that he discovered through his microscopes: he was a diligent observers of this new microcosm and counted and measured these new micro-organisms. His calculations were laborious and, being before modern standardisation, relied on unusual units. For example, comparing the width of 100 red blood cells as less the the diameter of a grain of sand.
Anthony van Leeuwenhoek was probably the discover of hundreds and hundreds of new species and micro-organism and opened up a whole new scale of the universe. Scientifically, his work really was as revolutionary as, say, the helio-centric model of the solar system; although I don’t believe van Leeuwenhoek ever relates his observations to God’s universe. His legacy is the collections of his letters and observations, his microscope designs and devices and, most importantly, the inspiration of almost 400 years of microbiologists, naturalists and microscopists.
My thanks go to Professor Douglas Anderson and colleagues for all their work on Lens on Leeuwenhoek, a database of collected documents, including letters and plates, events and other resources aimed at collating information about van Leeuwenhoek and his life into a taxonomical database. Much of the above information comes from reading these pages.