Pages tagged lenses

Leeuwenhoek's Microscopes

His microscope was a superior design because it solved his problems better than the alternatives. It was a dead-end design because it was too hard to make and much harder to use than the double-lens microscope.

Dead-end design

Once Leeuwenhoek had the instrument, he had to learn how to use it. Using it was so difficult that his design was never used by anyone else to make important discoveries. In the history of the microscope, it was a dead end.

Eel viewer - showcase for visitors

The pin on Leeuwenhoek's simple microscopes did not work for large living specimens. For example, Leeuwenhoek's showcase for visitors was a demonstration of the blood circulating through the capillaries in the tail of an eel. The eel had to be living if the blood were to circulate and a living eel would not stay still on the edge of a pin. So what would you do?

Focus

How did the parts work together? Positioning screw: The longest screw moved the mount, and thus the specimen, in two directions: up and down and back and forth. Focusing screw: This shorter screw moved the mount, and thus the specimen, in and out, that is, closer to or farther from the lens. It did this by pressing against the body plate, pushing it away from the specimen pin.

Hooke's observations

Micrographia: or, Some physiological descriptions of minute bodies made by magnifying glasses title page (left) illustrations showing Hooke's experimental method accompanying Observ. IX. Of the Colours observable in Muscovy Glass, and other thin Bodies (center) and Observ. X. Of Metalline, and other real Colours (right)

Hooke: "A single votary, Mr. Leeuwenhoek"

In February 1692, when as it turns out Leeuwenhoek was not halfway through his long career, Robert Hooke delivered a lecture about the history and future of both the telescope and microscope. Much the same has been the Fate of microscopes, as to their Inventions, Improvements, Use, Neglect and Slighting, which are now reduced almost to a single votary, which is Mr. Leeuwenhoek;

Tiny Lenses

The three methods Leeuwenhoek used to make his lenses:grinding, blowing, and drawing.

What happened to them?

Antony van Leeuwenhoek bequeathed twenty-six magnifying glasses to the Royal Society. They were duly described and catalogued, only to have "disappeared" from the archives by the mid-1800's. He gave two magnifying glasses to Queen Mary (while she was still wife of the Stadtholder of Holland, William of Orange). The rest, his will stated, should be sold "in a bundel". The executors of his daughter's estate complied two years after her death.