Simple microscope, Antoni van Leeuwenhoek, 1675-1725

This microscope was made by Van Leeuwenhoek himself. It is a very simple instrument. It consists of just two metal plates, into which a hole has been drilled at the same height. Between the plates, on a level with the holes, a small lens has been clamped. The whole is equipped with a construction of three screws engaged with each other. This serves at the same time to hold the instrument and to mount the object to be studied on it. Van Leeuwenhoek ground the lenses himself, but how he did it he kept a closely-guarded secret. Most of the approximately 500 lenses that he ground magnified between 25 and 100 times, but occasionally much more. With the best of his lenses he could see, for example, spermatozoa and monads. For his contemporaries it was often difficult to verify Van Leeuwenhoek's observations with their own eyes and microscopes.