Arjen Roelofs
Encyclopedia
Arjen Roelofs was a Dutch
astronomer
.
, as the youngest of four sons and two daughters. His father was Roelof Pytters, a tenant farmer and tax receiver. His mother was Neeltje Alberts from Finkum. The oldest son Klaas trained as a steersman, but did not work as one, and instead became a doctor in Sexbierum
. The other sister Lisbeth married and left the household. It was not an easy life on the farm, but this is where the other three boys, Pieter, Albert and Arjen had to work. Their mother stimulated the interest of the three sons in mathematics
and science
, however
their father was unhappy with this.
After their parents had died in 1790, the three brothers took over the farm, and their sister Antje became their housekeeper. None of these four ever married, and they all lived on the farm until they died. Arjen Roelofs was supposed to have had polio so he could not use his right leg very well, and later he could not work on the farm anymore. This enabled him to spend more time on his hobbies. Also his brothers joined him in his hobbies. Pieter was known as a mathematician
, but was also an excellent instrument maker
. Arjen designed telescope
s, and Pieter made them. Albert was a clockmaker
. Pieter and Arjen took meteorological measurements and made instruments to accomplish this. They made thermometer
s, hygrometer
s, and measured wind speed
and wind direction
.
regularly spent time at Hijum. He ensured that University of Franeker
professor Johan Henri van Swinden
became a very regular visitor. Roelofs also took on students. His cousin Roel Hessels Hommema, and his friend Rinse Bearts Gelder were taught in Hijum. Later Arjen regularly worked with instrument maker and farmer Sieds Johannes Rienks of Hallum
.
In 1817 they presented a plan for the construction of a telescope to the Dutch Government. The plan did not eventuate. However it did interest King Willem I
, who named both as Brothers in the Order of the Netherlands Lion on 23 September 1817. The brothers were also awarded a silver medal by Lodewijk Napoleon 7, on 20 June 1810. Arjen Roelofs made most of the calculations and measurements for Rienks for the building of the telescopes in Leiden and Utrecht
. Rienks had been commissioned to build these in 1818. The duo had a falling out during this project, and the quality of the telescopes suffered. The Leiden telescope, finished in 1821 was so bad that it was sold as scrap in 1845.
The telescope for Utrecht was never installed. Roelofs also calculated the times of solar eclipse
s for Rienks. During the eclipse of 7 September 1820 there were quite a number of people on the farm with Roelofs. His brothers already died some time before. Pieter died in 1801, and Albert in 1809. The governor of Friesland
, I. A. Aebinga van Humalda was present. Professors and their work associates from Franeker were there and also Eisinga.
Arjen Roelofs observed four transits of Mercury
. For three of these he made accurate predictions of the start and end times. His observations did not correspond to the orbital elements that were known at the time. If he had made this better known, a more accurate orbit for Mercury could have been calculated. Arjen Roelofs was too modest.
. Roelofs studied this by using a kite
. He invented a lightning rod. He employed Rienks to make them, and sold them for 30 guilder
s each.
After the flood disaster of 1825, Roelofs worked on dikes. He studied them to see if they could be improved. Roelofs made a proposal to the provincial government to build the dikes differently. Before this the sides of the dikes were steep and protected by wooden posts. These poles had been eaten by shipworm
. Roelofs proposed to get rid of the wooden posts, and to have the faces of the dikes more moderately sloped and covered with a sturdy layer of earth. Willem Loré had already thought of this, and it is not known if Roelofs was aware of Loré's ideas.
that passes the location of Hommema-sate was renamed Arjen Roelofswei. Also the school at Hijum is named after him.
. He was able to read Roelofs' hand written notes. Most of these have since been lost. The Eisinga Planetarium has a telescope made by Roelofs, and some of his manuscripts. Also the Tresoar in Leeuwarden has a small collection of manuscripts.
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
astronomer
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...
.
Early life
Roelofs was born on the Hommema-sate (estate) near Hijum in FrieslandFriesland
Friesland is a province in the north of the Netherlands and part of the ancient region of Frisia.Until the end of 1996, the province bore Friesland as its official name. In 1997 this Dutch name lost its official status to the Frisian Fryslân...
, as the youngest of four sons and two daughters. His father was Roelof Pytters, a tenant farmer and tax receiver. His mother was Neeltje Alberts from Finkum. The oldest son Klaas trained as a steersman, but did not work as one, and instead became a doctor in Sexbierum
Sexbierum
Sexbierum is a village in the municipality of Franekeradeel, in the central north of the Netherlands. The village is famous for its contraction of the words "Sex", "Bier" and "Rum"...
. The other sister Lisbeth married and left the household. It was not an easy life on the farm, but this is where the other three boys, Pieter, Albert and Arjen had to work. Their mother stimulated the interest of the three sons in mathematics
Mathematics
Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...
and science
Science
Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe...
, however
their father was unhappy with this.
After their parents had died in 1790, the three brothers took over the farm, and their sister Antje became their housekeeper. None of these four ever married, and they all lived on the farm until they died. Arjen Roelofs was supposed to have had polio so he could not use his right leg very well, and later he could not work on the farm anymore. This enabled him to spend more time on his hobbies. Also his brothers joined him in his hobbies. Pieter was known as a mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....
, but was also an excellent instrument maker
Instrument maker
Instrument maker can refer to:*A maker of scientific instruments*A maker of musical instruments**A luthier is a maker of stringed instruments...
. Arjen designed telescope
Telescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...
s, and Pieter made them. Albert was a clockmaker
Clockmaker
A clockmaker is an artisan who makes and repairs clocks. Since almost all clocks are now factory-made, most modern clockmakers only repair clocks. Modern clockmakers may be employed by jewellers, antique shops, and places devoted strictly to repairing clocks and watches...
. Pieter and Arjen took meteorological measurements and made instruments to accomplish this. They made thermometer
Thermometer
Developed during the 16th and 17th centuries, a thermometer is a device that measures temperature or temperature gradient using a variety of different principles. A thermometer has two important elements: the temperature sensor Developed during the 16th and 17th centuries, a thermometer (from the...
s, hygrometer
Hygrometer
A hygrometer is an instrument used for measuring the moisture content in the environmental air, or humidity. Most measurement devices usually rely on measurements of some other quantity such as temperature, pressure, mass or a mechanical or electrical change in a substance as moisture is absorbed...
s, and measured wind speed
Wind speed
Wind speed, or wind velocity, is a fundamental atmospheric rate.Wind speed affects weather forecasting, aircraft and maritime operations, construction projects, growth and metabolism rate of many plant species, and countless other implications....
and wind direction
Wind direction
Wind direction is reported by the direction from which it originates. For example, a northerly wind blows from the north to the south. Wind direction is usually reported in cardinal directions or in azimuth degrees...
.
Circle of friends
Eise EisingaEise Eisinga
Eise Jeltes Eisinga was a Dutch amateur astronomer who built an orrery in his house in Franeker, Netherlands. The orrery still exists and is the oldest functioning planetarium in the world.-Biography:...
regularly spent time at Hijum. He ensured that University of Franeker
University of Franeker
The University of Franeker was a university in Franeker, Friesland, presently part of the Netherlands. It was the second oldest university of the Netherlands, founded shortly after Leiden University....
professor Johan Henri van Swinden
became a very regular visitor. Roelofs also took on students. His cousin Roel Hessels Hommema, and his friend Rinse Bearts Gelder were taught in Hijum. Later Arjen regularly worked with instrument maker and farmer Sieds Johannes Rienks of Hallum
Hallum
Hallum is a small village in the province of Friesland, the Netherlands. It is part of the municipality of Ferwerderadiel. The primary language spoken there is Frisian. Hallum is also a relatively uncommon family name. There was a station on the North Friesland Railway which opened in 1901 and...
.
In 1817 they presented a plan for the construction of a telescope to the Dutch Government. The plan did not eventuate. However it did interest King Willem I
William I of the Netherlands
William I Frederick, born Willem Frederik Prins van Oranje-Nassau , was a Prince of Orange and the first King of the Netherlands and Grand Duke of Luxembourg....
, who named both as Brothers in the Order of the Netherlands Lion on 23 September 1817. The brothers were also awarded a silver medal by Lodewijk Napoleon 7, on 20 June 1810. Arjen Roelofs made most of the calculations and measurements for Rienks for the building of the telescopes in Leiden and Utrecht
Utrecht (city)
Utrecht city and municipality is the capital and most populous city of the Dutch province of Utrecht. It is located in the eastern corner of the Randstad conurbation, and is the fourth largest city of the Netherlands with a population of 312,634 on 1 Jan 2011.Utrecht's ancient city centre features...
. Rienks had been commissioned to build these in 1818. The duo had a falling out during this project, and the quality of the telescopes suffered. The Leiden telescope, finished in 1821 was so bad that it was sold as scrap in 1845.
The telescope for Utrecht was never installed. Roelofs also calculated the times of solar eclipse
Solar eclipse
As seen from the Earth, a solar eclipse occurs when the Moon passes between the Sun and the Earth, and the Moon fully or partially blocks the Sun as viewed from a location on Earth. This can happen only during a new moon, when the Sun and the Moon are in conjunction as seen from Earth. At least...
s for Rienks. During the eclipse of 7 September 1820 there were quite a number of people on the farm with Roelofs. His brothers already died some time before. Pieter died in 1801, and Albert in 1809. The governor of Friesland
Friesland
Friesland is a province in the north of the Netherlands and part of the ancient region of Frisia.Until the end of 1996, the province bore Friesland as its official name. In 1997 this Dutch name lost its official status to the Frisian Fryslân...
, I. A. Aebinga van Humalda was present. Professors and their work associates from Franeker were there and also Eisinga.
Arjen Roelofs observed four transits of Mercury
Transit of Mercury
A transit of Mercury across the Sun takes place when the planet Mercury comes between the Sun and the Earth, and Mercury is seen as a small black dot moving across the face of the Sun....
. For three of these he made accurate predictions of the start and end times. His observations did not correspond to the orbital elements that were known at the time. If he had made this better known, a more accurate orbit for Mercury could have been calculated. Arjen Roelofs was too modest.
Different projects
Arjen Roelofs was also busy with other activities. He developed lightning conductors, and better sea dikes. Farm houses were often struck by lightningLightning
Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...
. Roelofs studied this by using a kite
Kite
A kite is a tethered aircraft. The necessary lift that makes the kite wing fly is generated when air flows over and under the kite's wing, producing low pressure above the wing and high pressure below it. This deflection also generates horizontal drag along the direction of the wind...
. He invented a lightning rod. He employed Rienks to make them, and sold them for 30 guilder
Guilder
Guilder is the English translation of the Dutch gulden — from Old Dutch for 'golden'. The guilder originated as a gold coin but has been a common name for a silver or base metal coin for some centuries...
s each.
After the flood disaster of 1825, Roelofs worked on dikes. He studied them to see if they could be improved. Roelofs made a proposal to the provincial government to build the dikes differently. Before this the sides of the dikes were steep and protected by wooden posts. These poles had been eaten by shipworm
Shipworm
Shipworms are not worms at all, but rather a group of unusual saltwater clams with very small shells, notorious for boring into wooden structures that are immersed in sea water, such as piers, docks and wooden ships...
. Roelofs proposed to get rid of the wooden posts, and to have the faces of the dikes more moderately sloped and covered with a sturdy layer of earth. Willem Loré had already thought of this, and it is not known if Roelofs was aware of Loré's ideas.
Death
The farmer professor died at the age of 74 years, after a long illness. He was buried next to his brothers and sister at the grave yard at Hijum. The road from Oude LeijeOude Leije
Oude Leije is a hamlet in the municipality of Leeuwarderadeel in the Netherlands and has about 270 inhabitants. It is located on the river Dokkumer Ee, and is therefore on the route of the Elfstedentocht....
that passes the location of Hommema-sate was renamed Arjen Roelofswei. Also the school at Hijum is named after him.
Manuscripts
Roelofs could have done better than what he did. His problem was that he was too much of an individualist. He did not use tables, but would rather calculate everything himself. He also limited himself by being happy to stay in Hijum. He must have written quite a bit by necessity, but he did not ever publish. In 1829 a booklet titled Levensberigten van Arjen Roelofs (Life of Arjen Roelofs) was published by a farmer acquaintance Worp van Peyma from TernaardTernaard
Ternaard is a village in the municipality Dongeradeel located in the northeast of the province of Friesland between Dokkum and the Wadden Sea.| - History :...
. He was able to read Roelofs' hand written notes. Most of these have since been lost. The Eisinga Planetarium has a telescope made by Roelofs, and some of his manuscripts. Also the Tresoar in Leeuwarden has a small collection of manuscripts.