### Willebrord Snel van Royen was a 17th-century Dutch astronomer and mathematician who was also known as Willebrordus Snellius in most of his writings. Over the ages, he has been remembered for one of science’s most important discoveries: the law of refraction. Until recently, it was thought that he was the inventor of the theory; however, it was discovered that Ibn Sahl had formulated the law and that Snell had just rediscovered it. He was a mathematical genius who made several advances to the subject, despite having previously studied law. Snell, as he was known in the western world, ushered in a great revolution when he devised a new way for calculating the mathematical function ‘Pi,’ resulting in enormous progress in the field of mathematics. Snell had a number of works published, the most well-known and lauded of which are ‘Eratosthenes Batavus’ and ‘Tiphys Batavus.’ He traveled all around Europe at the height of his career, making further discoveries and working on a variety of results, particularly in the field of astronomy. He collaborated with the best in the astronomy world at this time, including Johannes Kepler and Tycho Brahe.

## Childhood and Adolescence

Willebrord Snell was born in the Dutch city of Leiden. Several historians are still unsure on the actual date of his birth. He is thought to have been born in the year 1580.

He was born to Rudolph Snel van Royen, a successful professor of mathematics at the University of Leiden, and Machteld Cornelisdochter, who named him after his paternal grandfather.

He was the oldest of three brothers and sisters. Jacob, who died at the age of 16 in 1599, and Hendrik, who died during his boyhood, were his brothers.

Rudolph Snell, a knowledgeable professor, maintained his own private school near the university. Snell earned his education at that particular school. Latin, Greek, and philosophy were taught to him by his father.

Aside from that, he didn’t have any further official education. Rudolph pushed his son to pursue a career in law, but Snell was more interested in mathematics due to his father’s influence. He became a private student of Ludolph Van Ceulen, a prominent German mathematician, because of his passion for the topic.

His father enrolled him in the University of Leidento to study law when he was of legal age. Despite this, he began teaching mathematics at the university when he was 20 years old, in the absence of his father. He was studying law and teaching mathematics at the university by the year 1600.

## Early on in your career

From 1600 forward, he traveled throughout Europe, primarily to understand astronomy. In Wurzburg, he paid a visit to Adriaan van Roomen. After a brief stay in the city, the two mathematicians traveled to Prague, where he met Tycho Brahe.

He also spent a lot of time with Brahe, supporting him in his observations, and as a result, he learned a lot during his visit. When Brahe died in 1601, the elevated knowledge gained while working with him came to an end. He also met Johannes Kepler, who was Brahe’s assistant at the time, during this tour.

In 1603 he moved to Paris to continue his law studies, although he maintained contact with a number of mathematicians, continuing to research and make observations. After this visit, he dropped out of law school and returned to Leiden.

When his father’s health began to worsen, Willebrord Snell began aiding him in teaching mathematics at the University of Leiden. The two created an excellent team, working together as academics for several years.

He was not an official professor until 1609, and had simply taken over his father’s lectures while he was ill. Slowly, he began to receive daily afternoon lectures, as well as an additional stipend for doing so.

Rudolph’s chair was given to his son when he retired, and he praised the chance because it allowed him to have a light teaching load. This allowed him to devote more of his time to the publication of translations, comments, and editions of notable mathematicians’ works.

## Interest in Geometry

Snell was intrigued to geometry and the proportions of the world in 1615, and he determined to develop a new method for calculating the planet’s radius. He came to the conclusion that using ‘triangulation,’ he could compute the distance between one place on the earth’s surface and another point’s parallel latitude.

In 1617, he published the results of his investigation in the book ‘Eratosthenes Batavus.’ He was having trouble finishing his task until Sterrenberg took over and helped him finish it. One of Snell’s contributions to modern geodesy is ‘Eratosthenes Batavus.’

He was instrumental in the resurrection of Apollonius’ works on the subject of ‘planar loci,’ as well as Pappus’ works. Under the title ‘The Revived Geometry of Cutting off of a Ration and Cutting off of an Area,’ he republished the works of these two great mathematicians. He continued to study Apollonius’ works and published a reconstruction titled ‘Apollonius Batavus’.

Following his father’s death, he encountered financial difficulties. Even though he was given his father’s chair, he was not adequately compensated for it. In February 1614, he was paid a greater pay, but it was still barely a third of that of other professors.

In February 1615, he was promoted to full professor of mathematics, although his stipend remained same. He gradually obtained tiny raises, but it wasn’t until 1618 that he received a wage that he felt adequate for his job.

## Major Projects of Willebrord Snell

He was frequently chastised for publishing discoveries he had developed based on the work of other mathematicians. As a result, he decided to produce a book detailing his own observations, and in 1619, he published ‘Descriptio Cometae,’ a study of comet movement. Snell also produced other works, including a treatise on nautical theories called ‘Tiphys Batavus’ in 1624.

He was able to enhance the way of determining approximate values of ‘pi’ using polygons thanks to his maths study. Using 96-sided polygons, this method produced a value of pi that was accurate to seven places, which was a revolutionary improvement over the previous method, which only supplied two places.

In 1621, he is credited with discovering the law of refraction, which was not published until 1703 in ‘Dioptrica.’ It also contained a document containing a book on optics that assisted him in formulating the’Law of Refraction.’

## Personal History and Legacy

He fell in love and married Maria de Langhe, the daughter of Janneke Symons and Laurens Adriaens de Langhe, a burgomaster of Schoonhoven, in August 1608.

Around seven children were born to the couple. According to some sources, he had roughly 18 children, as stated in his funeral oration. Several historians, however, have refuted this claim. Unfortunately, only three of his eight children lived to adulthood.

In 1626, he became quite ill with colic and sought the advice of reputable medical specialists. However, the medication they gave him didn’t help him recover from his sickness. He acquired a high fever as a result of colic, which rendered his arms and legs paralyzed.

The doctors came to see him on the evening of October 30, 1626, to check on his condition. They gave him a suppository to relieve him because they couldn’t find any improvement. His servants had to lift him and carry him around because he couldn’t move due to the immobility. He lost consciousness that night and died at the age of 46.

On November 4th, he was laid to rest at Leiden’s Pieterskerk. His casket was carried by twenty of his students.