Zacharias Janssen

Sacharias Jansen
Sacharias Jansen
Born	c.1585 The Hague
Died	c.1632
Citizenship	Dutch
Scientific career
Fields	Optics: Microscopy, Telescopy

Sacharias Jansen (c. 1585 - c. 1632) was a Dutch spectacle-maker from Middelburg credited with inventing, or contributing advances towards the invention of, the telescope. Jansen is sometimes credited for inventing the first truly compound microscope. However, the origin of the microscope - just like the origin of the telescope - is a matter of debate.

His name is often written as Zacharias Jansen or Zacharias Janssen, but as Dutch scientific literature writes the name as Sacharias Jansen, that way of writing it is also used in this article.

In 2008, the Netherlands commemorated the 400th anniversary of the telescope, honoring Jansen as one of the two possible inventors of the telescope, the other being Hans Lippershey.

Jansen's life

Sacharias Jansen's life was documented by the many investigations on the subject before the Second World War. Many of the Middelburg archives were destroyed by a devastating bombardment on May 17, 1940, during the Nazi invasion of the Netherlands. If there had never been profound investigations, we would not know anything of Jansen's life at all, since all files were lost in the fires following the bombardment. When investigating Jansen's life, especially a book written in 1906 by Cornelis de Waard, de extenso, is essential.

All data below is explained in a wider context in a book by Huib J. Zuidervaart of the Vrije Universiteit in Amsterdam that is to be published in the spring of 2008. The Public Observatory Philippus Lansbergen in Middelburg has already been shown a first version of the book.

Personal life

Jansen was born in The Hague in approximately 1585. His parents were Hans Martens and Maeyken Meertens, who both probably were from Antwerp, Belgium. He grew up with his sister Sara in Middelburg, at the time the second most important city of the Netherlands, and became a spectacle-maker. By choosing this profession, he became the direct competitor of Lippershey, who practically lived next door. The fact that they lived this close to one another would play a great role in the investigations on the invention of the telescope.

He himself stated he was born in The Hague on the marriage file of his first marriage, with Catharina de Haene, on October 23, 1610. When this file was refound by Cornelis de Waard in 1906, De Waard found the following excerpt: Sacharias Jansen, j.g. uut Den Haghe, translated into modern English: Sacharias Jansen, bachelor from The Hague Before, it was often thought Jansen actually was a native of Middelburg.

In 1611 their son Johannes Sachariassen was born. He would later testify under oath that Johannes Lippershey had stolen his father's invention of the telescope.

Following the death of Jansen's first wife in 1624, he married Anna Couget from Antwerp, who was the widow of some Willem Jansen (probably a family member of Jansen). He moved to Amsterdam in November 1626. He must have died before 1632, since his son Johannes declared his parents had died by the time he married in April 1632.

Breaking the law

hey party ppl

Inventions

Telescope

According to some , it was not Lippershey, but rather Jansen who invented the telescope. An important source is William de Boreel, who visited Middelburg to research the invention in 1655. Among his interviewees were Jansen's son and daughter. Boreel concluded that Jansen's telescope was finished about 1610. His research was referenced by Pierre Borel in De vero telescopii inventore.

The fact that Jansen is not well-known outside the Netherlands has to do with the patent Lippershey requested for the telescope in 1608. Whilst that news was spread across the world in just a few months (eventually Galileo Galilei heard about it), several investigations on the subject in the 17th, 18th, 19th and 20th century, stating Jansen might have invented the device, were only published and read in the Netherlands. To make it even worse, just one of the investigations was published in English and just that one stated Lippershey did invent the telescope, making Jansen even more infamous in countries outside the Netherlands. Several sources, however, indicate Sacharias Jansen constructed the first telescope in 1604, or even earlier.

Microscope

Jansen invented the microscope, probably with the help of his father, in 1595 while trying to find a way to make magnification even greater, to help people with seriously poor eyesight. Jansen is attributed to this discovery, though it is debatable.

External links

• Website about the 400th anniversary of the telescope