Prior to its incorporation into the collection of scientific instruments and teaching aids, this anemometer – also referred to as a cup cross anemometer – was part of the former Rübel Geobotanical Research Institute. The collection is now home to 71 objects from this institute. They include some of Eduard Rübel’s personal items such as his thermometer (below left) or his compass (below right).
Measuring wind speed using the anemometer
Zurich geobotanist Eduard Rübel (1876-1960) was one of the main promoters of geobotany in the early 20th century — a research field which was still young at the time. The methodological standardisation of the subject was also an important matter to him.1 He wrote Geobotanische Untersuchungsmethoden [Geobotanical Research Methods] in 1922 to this end. In this book, he defined various parameters of geobotanical research and described how the different research instruments function. The 3D digitalised anemometer is also described here: “The apparatus is easy to carry: it is only 15 cm high and, at the cup cross, as at the pointer clock, only about 6 cm wide.”2 This was extremely important for the field research, as several instruments had to be carried and set up in the field.
An anemometer is used to measure the wind speed over a certain period of time. This allows the average wind speed or wind force to be calculated. Since the cups are facing in all directions, they show any wind strength from any direction equally. In his book, Rübel provides an example of measuring wind strength using this anemometer: The unit of time for the measurement is 100 seconds. The counter shows how many metres the wind has travelled within this time unit. If you measure a wind path of 484 metres in 100 seconds, this results in a wind force of 4.84 m/s.
The anemometer was developed by astronomer Thomas Romney Robinson (1792-1882). Robinson, who was intensively involved in meteorology, invented the anemometer with hemispherical cups in 1846. The anemometer originally consisted of only two shells. To balance the rotational force, another pair of shells was later crossed. Anemometers such as these are still in use today. The collection of scientific instruments and teaching aids comprises other such instruments from different eras and disciplines. These can be viewed in the online catalogue.
Eduard Rübel and Rübel Geobotanical Research Institute
Rübel studied chemistry at ETH and, having obtained his doctorate in 1901, became an assistant to botany professor Carl Schröter. Rübel was appointed private lecturer for Botany at ETH in 1917, and senior professor in 1923.
photographer: Rübel, Eduard August / Dia_282-0661 / CCBY-SA 4.0
Geobotanisches Forschungsinstitut Rübel [Rübel Geobotanical Research Institute was founded by Eduard Rübel in 1918. The aim of the foundation was to promote the discipline of geobotany, which was still young at the time, as well as to foster the exchange between different (geo)botanical institutes. The institute provided researchers with access to a large library as well as the facility to borrow various scientific instruments for use in their research. Some of these instruments were preserved and transferred to the collection of scientific instruments and teaching aids in 2020 and 2022.
The institute became very well known and shortly outgrew the room in Rübel’s house at number 30, Zürichbergstrasse. With the support of his sisters Helene and Cécile, who donated a building fund, Rübel established a new institute building at number 38, Zürichbergstrasse.
ETH library, picture archive / photographer: Unknown
/ Dia_282-0087 / Public Domain Mark.
Rübel remained director of the institute until 1928. He donated it to ETH and relinquished responsibility for it in 1958, at the age of 82. Upon this donation, it was re-named Geobotanisches Institut an der ETH, Stiftung Rübel [Geobotanical Institute at ETH, Rübel Foundation.
The institute no longer exists in its original form: The two professorships of the Geobotanical Institute (Plant Ecology and Ecological Plant Genetics) were incorporated into the newly founded Institute of Integrative Biology in the Department of Environmental Systems Sciences at ETH Zurich in 2006. The foundation established by Rübel still exists.
3D Digitalisation
Object selection
We selected the cup cross anemometer because it represents the fine collection of Eduard Rübel, which is not otherwise represented in this series of 3D digitalisations. Many of these instruments from Rübel’s collection, including this anemometer, were intended for field research. The instruments had to be well packed when used for field research to prevent them from sustaining any damage on the way. The wooden box therefore belongs to this object, which is why we have also digitalised it. Thus, you can clearly see how the wooden box was also the holder into which the instrument was screwed. But the animation also shows how the moving pendulums set the clocks’ counters in motion, allowing the metres travelled to be measured.
Photogrammetry and modelling
The anemometer made of black painted metal was imaged well using photogrammetry, as was the wooden box. The latter was digitalised separately in open and closed states and only merged with the anemometer afterwards. The glass of the counting wheels and the animated structures were created manually.