The Collecting of Science // The Science of Collecting

For almost 185 years, TU Delft has been acquiring a rich variety of historical objects. These objects reflect the development of the university, as well as its technical research and teaching. Some are centrally managed by the TU Delft Library, whilst the rest are held at the faculties. With everything from architectural models to satellites, they demonstrate the breadth of subjects taught on campus. 

But when does a group of objects become a collection? It is not just a shared history or location- a collection needs to be tangible, with a defined purpose and a clear sense of its limits. For the last four years, the Tailor-Made Approach to Faculty Collections programme has worked to transform the historic objects found in the faculties into official collections for the TU Delft. 

This was not a simple assignment. Objects first needed to be located: a lengthy process of opening boxes and faculty basement doors. Once found, they had to be researched, gathering information by talking to university staff and external experts. Only once every object had been identified could a collection be defined, and the objects registered, photographed, and stored.

The TU Delft is not a museum. What this means is that the collections on campus are not intended to be displayed behind glass but are for active use in teaching and research. Whilst some pieces will always be too fragile to be passed around a lecture hall, most collections on campus contain objects that are intended to be freely handled and used.  

Some collections aim to give users a literal feel for the subject matter, such as the historic appliance collection at the faculty of Industrial Design, or the aircraft parts at Aerospace Engineering. Others are intended as a visual aid, like the collections of molecular models at the faculties of Mechanical Engineering and Civil Engineering & Geosciences. Still more are made by students themselves, such as the freehand drawings and architectural models made as part of courses taught at Architecture and the Built Environment. What these collections demonstrate, is the diverse landscape of successes and failures, of how designs developed through experimentation and observation, and of how the university and its research stands in the broader society.

Dr Abraham “Bram” van Heel (1899-1966) developed his alignment method during the Second World War. It was based on Young’s double slit experiment (1803) and Fresnel’s theory (1816) which demonstrated the wave behaviour of light with a double slit. Van Heel put his method into practice during post-war reconstruction, rapidly rebuilding the Hedel bridge's 126-metre span. The alignment method could accurately determine the positions of the bridge arch and pier supports to tenths of a millimetre. This meant that the bridge could be constructed simultaneously at two separate locations - the piers in Hedel and the span in Delft - shortening construction time by months.

Van Heel's preference for simple and practical solutions eventually led to his highly accurate alignment method that worked even over long distances. His philosophy of "do it with simple equipment" can be clearly seen in how he achieved his method. Van Heel was not satisfied with the alignment devices commonly in use at the time, which ranged from simple steel wire to expensive, high-quality optical instruments mostly imported from Germany.   

Even measurements from quality equipment were affected by aberrations and unwanted bending of light (“diffraction”). However, this is where another Van Heel motto- "make your enemies your friends- comes into play. His alignment method works by making use of these optical phenomena.

Using a “zone plate” with concentric circles, Van Heel aligned three points- the source point, an equidistant sun plate, and the crosshair on an eyepiece- to form a straight line. The zone plates create an interference pattern which allows for a very precise alignment. When light shines directly onto the zone plate, the rays form a circular interference pattern. When the crosshair is in the middle of these circles, all three points are aligned. With the placement of the grating, you can create a perfect line to align two points, such as the two halves of a bridge.

by Prof.dr.ir. Nitesh Bharosa

by Dr. Seda Gürses

by Prof. dr. Jeroen van den Hoven

by Dr. Anneke Zuiderwijk

How can historic objects be made relevant for today’s students? Why should students look to the past? In EE1G1, Introduction to Electrical Engineering, students first learn where computing came from. Before learning to code, first-year students are taken through the history of computation itself, using objects from the Study Collection as touchstones.  

Slide rules and abacuses as early assistive calculation tools, a magnetic core memory plane that stored bits as tiny magnetised rings, and a mechanical relay-based adder that performed binary arithmetic with electromechanical switches decades before transistors existed. Seeing and handling these objects gives students a tangible sense of how far, and how fast, computing has travelled, and grounds their first lines of code in a much longer story.

This mechanical calculator, known as "The Millionaire", demonstrates the best of 1890s precision engineering. Using an ingenious system of gears and cams, it was the first (commercially successful) mechanical calculator that could perform a direct multiplication, which dramatically increased the speed of complex arithmetic at the time. Rather than calculating multiplication as a long series of additions, its mechanism was based on a mechanical representation of the multiplication table. Around 5000 of these machines were produced worldwide between 1893 and 1935.

Every year, botanical gardens take stock of the seeds harvested from their own gardens, as well as any excess gathered during collecting trips. They publish this information in an ‘Index Seminum’ (Latin for ‘seed index’), which is then distributed and shared to participating gardens, arboretums and research institutions who can request any of these seeds free of charge. The publication of an Index Seminum has been an annual task for botanical gardens for centuries. 

Collecting and sharing seeds has always been a vital way to obtain diverse botanical material. Herman Boerhaave kept an ‘Index Seminum Satorum’ between 1712 and 1727 for the Hortus Botanicus in Leiden, which listed the seeds he received from other gardens. This practice was standardised throughout the 18th century, until it became the annual exchange of published that continues into the present day. TU Delft Hortus Botanicus  published their first Index Seminum in 1919.

Not all of the seeds kept at the Hortus are intended to be grown. One example of this is the historic seed collection, an almost complete collection of non-viable seeds collected between the 1890s and the late 20th century. During the garden’s off-season in 2025, Hortus staff repacked and relabelled almost 12,000 vials containing the collection. updating the records and adding modern names of previously colonial territories. Thanks to their hard work, the seed collection is now accessible to researchers. 

Non-viable seeds were originally intended to complement the Hortus’ herbarium (preserved plants) as part of its original role as a ‘technical garden’ to aid in the study of technical botany. Seeds from the same plant, one gathered a century before the other, can be monitored to see how seed traits and genetics have shifted over time. For this reason, seed collections remain an essential resource in tracking climate- related changes.

Seeds can unite the world. In the 1940s, botanists in China heard reports of a huge unknown tree in the village of Modaoxi in Luchuan County, Hubei. After studying the seeds they had collected, it became clear that they had found a ‘living fossil’: a species only known to botanists through the fossil record. Up until this point, it had been assumed that the Metasequoia glyptostroboides, or ‘dawn redwood’ had been extinct for 150 million years. 

In July 1947, Harvard University funded an expedition to acquire Metasequoia seeds for their collection. The timing of this proved fortunate; it was one of the last collaborations between American and Chinese botanists before the proclamation of the People’s Republic of China in 1949 prohibited exchange with the West.

This rocket motor test unit was developed by Volvo in collaboration with the European Space Agency (ESA). It is associated with the development and testing of propellant formations, material durability and nozzle designs for the first stage of the Ariane 4 launch vehicle. Securing the motor static test stand, engineers can precisely measure the physical performance, ensure system reliability, and validate engineering models. The complex network of pipes, valves and instrumentation enabled engineers to closely monitor and adjust operating conditions during experimental runs, generating vital data for the advancement of European rocket technology.

Science is teamwork, rarely possible in a vacuum. It creates a network between research teams, and throughout the university and its technicians, support staff, and research collections. It also connects with colleagues in the field, companies, and research institutions. Science creates an unbroken line, constantly building on previous theories to come up with the next idea.

The TU Delft collections are older than the university itself. They demonstrate the long and interconnected history of cooperation between different fields of research, between the university and institutions, and between the past and the present. However, many of these collections had become neglected and required attention. For the past four years, the Library Tailor-Made Approach to Faculty Collections programme has been working to bring these collections and their stories back to life.

A scientist is nothing without their instruments that can show the world from a new perspective. Researchers and instrument makers have often worked closely together to get the instruments exactly to their specifications, as shown by the instrument workshops in several TU Delft faculties. This can not only impact the research of the university, but also the teaching of future generations. 

Dr Carolina (Lili) E. Bleeker (1897 – 1985) was an optical scientist and physicist from the first half of the 20th century. She defied the gendered expectations of the time by founding the Nederlandse Optiek en Instrumentenfabriek Dr. C.E. Bleeker (Nedoptifa) in 1931. Her factory in Zeist produced the phase microscope that secured Zernike the Nobel Prize in 1953. She also had worked closely with scientists of the TU (then TH) Delft, which made much use of her optical instruments.

Sometimes you need family to solve a problem, or at least a good colleague. TU Delft (then TH Delft) prof. dr Willy G. Burgers (1897-1988) was well known in his field of physical chemistry, later known as material sciences. His brother Jan M. Burgers (1895-1981) was an even better-known physicist and a also professor in Delft, and later at the University of Maryland (USA).  

Their challenge: solving the unpredictable imperfection of materials. At first glance, crystals appear ordered with their atoms arranged in repeating patterns. Yet beneath the surface lie tiny structural irregularities known as dislocations - defects that can profoundly influence how materials behave.