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describe the compound microscope developed by zacharias and hans janssen


Describe the compound microscope developed by zacharias and hans janssen


a magnifier composed of a single convex lens

Hans and Zacharias Jansen complete microscope:

A complete microscope history

Zacharias Jansen (c. 1580 – c. 1638) was a Dutch spectacle-maker from Middelburg credited with inventing the first microscope. Although Zacharias Jansen’s life was previously documented, many of the archives were lost in the fires following the German bombardment of Middelburg during the Second World War on May 17th 1940.

Although Zacharias Jansen (often written as Zacharias Janssen, or Sacharias Jansen) is generally believed to be the first creator of a compound microscope, the accomplishment is dated around the 1590’s, so many scholars believe that his father, Hans, must have played an important role in the creation of the instrument. The pair worked together as spectacle makers in Middleburg, the Netherlands, not far from Hans Lippershey, another optical scientist who is also sometimes credited with the invention of the microscope, but more often with the creation of the first telescope.

Similarly, Zacharias Jansen is also sometimes credited with the invention of the first telescope, however its origin, just like the origin of the first compound microscope, is a matter of debate.

During the 1590s, the two Dutch spectacle-makers began experimenting. They put several lenses in a tube and made a very important discovery – the object near the end of the tube appeared to be greatly enlarged, much larger than any simple magnifying glass could achieve by itself.

Zacharias Jansen wrote to William Boreel, a Dutch diplomat who was a long-time acquaintance of the Jansens, to tell him about the magnifying device, although Boreel did not see the microscope for himself until years later. During the 1650s when the physician of the French King publicly sought information regarding the origin of the microscope, Boreel recounted the instrument’s design and his experience surrounding its use.

The first microscope

Jansen’s microscope consisted of three draw tubes with lenses inserted into the ends of the flanking tubes. The eyepiece lens was bi-convex and the objective lens was plano-convex, a very advanced compound design for this time period. Focusing of this hand-held microscope was achieved by sliding the draw tube in or out while observing the sample. The Jansen microscope was capable of magnifying images approximately three times when fully closed and up to ten times when extended to the maximum. No early models of Janssen microscopes have survived, but there is a candidate housed in the Middleburg Museum in the Netherlands that some historians attribute to Jansen.

Though rudimentary when compared with modern microscopes, the Jansen microscope was an important advance from single lens magnification. By the end of the seventeenth century, further developments, notably by Anton van Leeuwenhoek and Robert Hooke allowed the observation of organisms such as fossils, diatoms, as well as the first cells.

Since then, modern microscopes have been at the forefront of scientific development, capable of magnifications greater than 1000x.





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