The discovery by Anton van Leeuwenhoek of tiny creatures living in pond water stunned the scientific world.
The discovery by Anton van Leeuwenhoek of tiny creatures living in pond water stunned the scientific world.
Its importance was quickly realised, as was that of the microscope, which has literally given humanity a new view of the world.
People had known of the magnifying properties of lenses since ancient times.
Simple, single-lens microscopes had been in use since the early 16th century and compound microscopes, with more than one lens, were invented around 1590.
Leeuwenhoek, a Dutch scientist and tradesman (1632–1723), was inspired to make and use them by a best-selling book, Micrographia, produced in 1665 by English scientist Robert Hooke (1635–1703).
It contained Hooke’s stunning illustrations of a variety of magnified specimens, including woven cloth, a fly’s eye, human hair and a flea enlarged to 45cm (18 inches) across.
Leeuwenhoek made a variety of microscopes by grinding his own lenses. Some could magnify by a factor of 270.
He noticed tiny single-cell creatures in pond water and called them ‘animalcules’. Nowadays we call them micro-organisms.
Leeuwenhoek – since dubbed the ‘Father of Microbiology’ – also observed bacteria and sperm.
Microscopes at that time produced distorted images at high magnification.
Later 19th century microscopes produced clear images at very high magnifications by improving the manufacture of lenses and combining several at once.
This new generation of instruments could probe inside cells, revealing a host of tiny structures.
In the 1870s, German physicist Ernst Abbe (1840–1905) realised there is a limit to the magnification of an optical microscope (one that uses light) – it cannot ‘see’ objects less than two thousandths of a millimetre across.
Scientists found a way around this, by using a beam of electrons to illuminate the specimens – the electron microscope was invented in 1933.
Electron microscopes, which produce images on a television screen, revolutionised the study of biology just as their predecessors had done.
In 1981, researchers at the computing firm IBM invented a new kind of microscope, the scanning tunnelling microscope.
This does not produce images using light or electrons. Instead, it has a tiny probe that ‘feels’ its way across the surface of a specimen, following the incredibly minute lumps and bumps formed by the atoms themselves.
The image has to be visualised by a computer.
