3D Collection – a Tellurion for School

This tellurion is part of the Observatory Collection. It was created by Rudolf Wolf (1816-1893). He was a professor of astronomy, head of Semper Observatory, director of the library of the Polytechnic (today ETH) and collector of astronomical instruments. The collection was continued by his successors Alfred Wolfer and William Otto Brunner, although to a lesser extent and without the same systematic approach. The tellurion dates from the end of the 19th century and therefore could only have been added to the Observatory Collection after Rudolf Wolf’s death in 1893. As it is not listed in Rudolf Wolf’s inventory, the manner in which it was added to the collection is impossible to determine.

A teaching aid for school

Tellurions were used to understand the movements of the Earth and the Moon in relation to the Sun, as well as all illumination phenomena on the Earth and the Moon, since these cannot be observed “in reality”1. According to the instruction manual that was enclosed with the tellurion. In addition: “Thus, a tellurion is indispensable for school lessons.”2

In the tellurion, the sun is represented as a candle. A spring is installed in the base of the candlestick, ensuring that the flame always remains at the same height. The earth, in turn, is represented by a small, slightly angled globe. The earth rotates exactly 365 times around its own axis during one revolution. The moon is represented by a shiny silver globe, the size of which is in correct proportion to the size of the earth.

Ernst Schotte & Co

The tellurion was constructed by Ernst Schotte, who was founder of the Ernst Schotte & Co. geographical and artistic institute. Ernst Schotte & Co. made only minor changes to the original form.

Founded in Berlin in 1855, Ernst Schotte & Co. was a well-known manufacturer of globes and planetariums, also producing tellurions in various sizes. It existed until 1940.3

According to the inscription, our tellurion was designed and drawn by Heinrich Albrecht. However, since it was manufactured by Ernst Schotte & Co., it is probably a later version of the original tellurion. The enclosed instruction manual, also written by Heinrich Albrecht, dates from 1903, but the tellurion is somewhat older, dating from around 1885-1900.

The instruction manual

The tellurion offers multiple possibilities for teaching, as impressively shown in the 1903 instruction manual which has been completely digitalised and can be browsed through below:

3D Digitalisation

Object selection
The tellurion, which is over 100 years old, is in good condition, but the mechanics hardly work any more and the moon can no longer be placed in the correct position. Using the 3D model, the tellurion can be moved and the motions of the earth and the moon can be tracked. The moon was digitalised separately, which meant that it could be placed in the correct position retroactively. The fact that it no longer stays in place in the original is not visible in the 3D model. Since the original can no longer be demonstrated, we will certainly show the 3D digitalised tellurion during guided tours. It would be nice if it were used by schools also.

Photogrammetry and modelling
The tellurion was digitalised in several individual parts: the frame with the earth, the moon and the disc that can be placed on top were digitalised separately. The individual parts were easy to digitalise. The mechanical and animated elements were modelled manually using the scan template. The original object is missing the candle. Since it represented the sun, it was added to the 3D model to further elucidate the tellurion’s mode of functioning.

1. Schottes Tellurium mit Lunarium und seine Anwendung. Ein Leitfaden für Lehrer und Schüler von H. Albrecht, Berlin 1903, pg. 5.
2. ibd.

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