History: Prof. Dr. Ir. J.L. van Soest (EN)


Prof. Dr. Ir. J.L. van Soest (1898-1983)

Professor Van Soest or Johan Leendert van Soest was an extraordinary person. This is true from a scientific point of view because he became internationally known in two completely different scientific fields. But it applies at least so strongly to his person because he had ideas that can still be called modern.

Van Soest behind his desk as director of the Measurement Building (photo: mid-1930s)
Van Soest behind his desk as a young director of the Measurement Building (photo: mid-1930s)

Van Soest as a Scientist

Johan van Soest was born in 1898 as the son of the painter Louis van Soest. He belonged to the Hague School and was Queen Wilhelmina’s teacher for some time. Johan attended HBS [Hogere Burgerschool, an upper-level secondary school] in Arnhem and had a great interest in mathematics, chemistry and biology. His interest in mathematics already led to the question at HBS why it is possible to catch the circle and the ellipse in a mathematical formula, but not the egg shape. He thought about this and wrote an article for the Mathematical Journal when he was 21 years old, his first publication. Hundreds more would follow.

His interest in chemistry led him to conduct experiments in the coach house at his parents’ home. The result was a major explosion. He then decided not to study chemistry, but electrical engineering. After graduation, he joined the Commission on Physical Armament on February 15, 1927. He became director of the research laboratory, the Measurement Building, which started on the Plains of Waalsdorp on December 1, 1927.

The war period

On July 1, 1941, the Measuring Building was incorporated into the State Company of the PTT as a “Physical Laboratory” on the orders of the German occupier because TNO – given the uncertain time – did not dare to take over the Measuring Building. In July 1941, the transformation of the Laboratory for Physical Armourment into a National High-Frequency Service was considered. That didn’t work out. In 1943, the laboratory moved to the PTT complex at the Binckhorstlaan in The Hague. In mid-1943, Van Soest came into conflict with the new director, a member of the national socialist party. He had to hand over the management of the Physics Laboratory to one of his employees. He ended up in a ‘forgotten position’ in the Radio Laboratory.

In this new position, he was assigned to conduct research into a more efficient organisation of the PTT Research and Development structure with three laboratories. His report was issued on April 17, 1945; just before liberation. This led to the establishment of the Central Laboratory PTT, which included the Physics Laboratory, consisting of half of the workforce of Van Soest’s laboratory. C.E. Mulders, a former employee of the Physics Laboratory, led the PTT Physics Laboratory. Falling under the Ministry of Defence, Van Soest became the director of the Physics Laboratory Defence. End of 1947, early 1948 he and his staff returned to the old laboratory location on the Waalsdorpervlakte. In 1947, the Physics Laboratory of the Defence Department became part of the National Defence Organisation TNO (RVO-TNO).

Information theory at the Technical University Delft

In 1945, Johan temporarily replaced a professor at the Technical University Delft who had been suspended due to his attitude during the war. A number of his later employees graduated from him, including Y. Boxma. On 1 May 1948, Van Soest was appointed as an officer in the Order of Orange-Nassau.  In 1949, Johan was appointed as an endowed professor for one day a week. He decided to start lecturing in a new field, information theory. This theory was introduced in 1948 by the American Shannon. Johan felt that information theory could become the basis for equipment for transmitting information and working with information in the future and that this could mean a breakthrough. He was the first in the Netherlands with this vision.

But also very special was the fact that he saw this theory much more broadly, for example as a basis for social problems in which information plays a role. The lectures he gave on Saturday mornings were brilliant and attracted enormous interest. He took part in many conferences on information theory and achieved great international fame. Many organisations appointed him an honorary member. 

Johan was actually non-technical. He definitely had two left hands. He once proudly said that his neighbors had asked him for help when their television did not show a picture. He was, after all, an electrical engineer. He didn’t have a television himself and he had no idea how such a device worked. He looked deeply at the device, then remembered seeing a technician in the laboratory punch an electronic device in desperation when it failed to work. So he hit the television set and then there was a picture.

In 1957, he stopped working at the TNO laboratory. So he took something like early retirement. Ir. Y. Boxma was allowed to succeed him. Their scientific discussions continued. In 1964 he also retired in Delft. Again, Boxma became his successor as professor of information theory.

Prof. Dr. Ir. Van Soest
Prof. Dr. Ir. Van Soest

His farewell speech in Delft in 1964 was entitled “Farewell and is not a farewell“. He told us what he was going to do next. He was very attracted to cosmology, in particular the possibility that an antiworld still exists throughout our world. The Chancellor asked him whether he had given a farewell speech or an inaugural speech.


The biologist Van Soest

But electrical engineering was not his only scientific work. He still had a great interest in biology. As early as the 1920s, he started researching vegetation in the Arnhem area. He noticed the big difference between the vegetation along the river and on the sandy soils and decided to find out exactly. He noted down the plants he observed in ‘hourly pens’ and continued to do so until he had covered the entire country (an hourly pen is a piece of land measuring 5 by 5 km). This was characteristic of Johan’s way of working, systematic and persistent. In 1932, this enormous work was completed and a map of the plant geographical districts in the Netherlands appeared in the Dutch floras. This research is still of great value. He called it a bit ‘Playing Games’. 

Boxma saw the map during his HBS education in 1935 and thought that Ir. J.L. van Soest had to be a Wageningen bio-engineer.

Plant geographical districts in the Netherlands by Ir. J.L. van Soest (1932)
Plant geographical districts in the Netherlands by Ir. J.L. van Soest (1932)

Johan continued in botany and looked for an area no one had wanted to explore until now. He chose the dandelion, the genus Taraxacum, and with his systematic and persistent approach investigated the distribution of this plant throughout the world, as far as the Himalayas. He discovered new species in addition to the already more than a hundred known species and gradually became internationally regarded as the specialist in the field of the dandelion. Two new species he discovered were named after him and his wife: Taraxacum vansoestii and Taraxacum wijtmaniae. He continued to work on it until his death on October 30, 1983. He received dandelions by post from many countries with the request to identify them. He also wrote the taraxacum floras of the Netherlands, Belgium, Switzerland and Iran. Various international associations in this field also appointed him an honorary member.

Dandelion (Taraxacum)
Dandelion (Taraxacum)

Particularly honourable was that the University of Utrecht awarded him an honorary doctorate in 1958, with particular reference to botany.

Honorary promotion of Professor Van Soest, University of Utrecht (1958)
Honorary promotion of Professor Van Soest, University of Utrecht (1958)

The person Van Soest

Van Soest managed in an inimitable way to turn the people he gathered around him into one big family. He believed that any form of research required good cooperation within a group of people. He showed that everyone in the group was important. He often subtly suggested an idea and if someone picked it up he gave them full credit.

He was very systematic in his work and recommended this to others, for example, the students with whom he felt very connected. But he thought that they should also do something else in addition to their studies. In his inaugural lecture in Delft, he gave the students the following advice: “You will have to be economical with your time to remain a human being in addition to being an engineer. Keep order and system in your thoughts and your work, and adopt a system for this, it does not matter which one; my example was botanical systematics.

In daily life he was less systematic. As a result, there was once an embarrassing incident involving a suitcase. Shortly after the war he had to go to Canada with Admiral Pinke and from there to Washington, of course by boat and train. Because Pinke was so much older, Johan thought he should carry his second suitcase. When he arrived in Washington, he told Pinke to take care of his suitcase himself. To which Pinke shouted: “But that’s not my suitcase.” 

He also had no idea about cars and car brands were completely foreign to him. An Army colonel once told me in annoyance that Johan had ridden with him and had not noticed that he had a new car of which he was so proud. He then asked Van Soest if he had not seen that he had a new car. Whereupon Johan started, asked what brand it was, quickly looked at the dashboard and said: “Oh, I see it. A Philips.” I don’t know whether this was ignorance or teasing, because he had a special kind of humour.

Based on his broad knowledge of various fields, he was appointed chairman of the Royal Society of Physics under the motto Diligentia in The Hague and owner of the Diligentia building. He remained so for ten years and managed to stimulate both the annual lecture series and the rental of the hall. 

Johan could be very absent-minded. He always forgot where he hung his coat. As a result, he often came home with the wrong coat. He found something to it. From then on there was a pine cone in every jacket pocket. He always attended performances of the Chamber Music Association with his wife. On such an occasion his wife advised him to dress up. When he didn’t return, she went upstairs to check. He had put on his pajamas and was lying in bed and sleeping.


He had a wonderfully clear vision of the future, as evidenced by a manuscript from 1960 in which he drew a parallel between the development of energetic machines in the nineteenth century and the foreseeable development of information machines. He argued that around 1800, work and energy were precise basic concepts in physics. In technology, the possibility arose to build energetic machines, such as the steam engine. These machines could replace human or animal labour in the production of goods. This created unemployment, resulting in an economic and social crisis. But later, it was unthinkable that humanity could lead a decent existence without energetic machines.
He believed he observed a parallel phenomenon because natural science had accepted the concept of information. It should be possible to build information machines based on information theory. He foresaw a strong miniaturization and thus a broader application and wondered whether in the future these information machines will take over all kinds of routine work, such as accounting and organizational work, and thereby make life more pleasant. He also expected that in 40 years (around 2000!) every student would own a memory machine and that every household would have a calculator. But he also wondered whether society should not be warned about possible adverse consequences of unemployment.

He was also very concerned about the environment at a time when no one was concerned about it. He saved all the envelopes and used them as scrap paper. At home, he tried to be economical with energy and many people were surprised by this. In a lecture for the Dutch Radio Society in 1964, he said about our environment: “Today’s man, who feels himself Lord on earth, manages it badly, particularly badly. He destroys his environment. He poisons the air, it spoils the water, it mars the ground. It devours energy, however often unnecessarily and with poor returns. Does humanity have a conscience about these things? Undoubtedly! But is this reflected in our society? Hardly! At the current time, everything is in the shadow of an economic order and vision.

He demanded reflection on all achievements. So you had to ask the question: What do we do with it? Not only do we not allow incorrect applications, but we also require that technical achievements be properly preserved. Morality was very important to him in this context. In 1964, he said in the same lecture for the Dutch Radio Society that morality is the doctrine of duties and virtues. We do with our will what our morals tell us. This means that morality is the a posteriori conclusion from the past and that you use it as an a priori guideline for the future. The duty that is important here lies somewhere between freedom and bondage. So with every problem, you have to look for harmony between them.

Johan was almost a caricature of the absent-minded professor. One day he was desperately talking on the phone when an employee came in: “Look at my other suit. They have to be somewhere.” The employee asked him what he had lost. “My keys“. The employee then pointed to the bunch of keys dangling from his little finger.


    1. This text was largely derived from the lecture for the Rotary Club Zoetermeer by Prof. IJsbrand Boxma on November 1, 2006.
      (Additions and refinements are based on the following sources) 
    2. The KPN Research – TNO relationship.
    3. Notes by Van Soest (Waalsdorp Museum archives).
    4. Development at Royal KPN: A History of the First 100 Years of Postal and Telecommunications Research in The Netherlands, D. van de Nieuwe Giessen, 2001.
    5. B.J.M. Verschoof. (1978). Professor Dr. Ir. J.L. van Soest tachtig jaarGorteria Dutch Botanical Archives9(5), 118–120