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| Hooke's Importance for Microscopy |
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The Englishman Robert Hooke built one of the first compound microscopes in 1660: He used an oil lamp as a light source. Using a concave mirror, the light was directed to the object via a converging lens. The microscope itself consisted of four extendible concentric tubes. Its optics consisted of an object-side lens, a field lens and the eyepiece. A large field of view was obtained by using all lenses. For more exact observation of the object, he omitted the middle lens.
To set the distance between the objective lens and the object, he had the entire tube raised and performed additional fine adjustment using a screw drive at the end of the tube. Unlike the tripod stands of other microscopes at that time, he used a round plate as a stand. Hooke determined the magnification of his microscope by looking simultaneously into the microscope with one eye and at a scale lying beside the microscope with the other.
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| Robert Hooke's compound microscope: on the right the illumination device, on the left the microscope which was used with incident light. | The front cover of "Micrographia". | Drawing of a louse from "Micrographia". |
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The publication of Hooke’s Micrographia in 1665 marks one of the milestones in British science. This book contains numerous drawings of objects he viewed with the microscope: a bee sting, a razorblade, snow crystals, wood, cork and insects. He also created his own technique for the production of thin sections. In 1667 his studies on the composition of cork led him to suggest the use of the term ”cell”, paving the way to the utilization of the same word in today’s life sciences to describe the basic constituents of all living creatures.
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