Surveying has been an important part of the educational offerings, which is why a platform was built on the roof of the Urbygningen and later a tower on the Tårnbygningen
Surveyors appreciated a good view to practice their measurements in the old days. Today, GPS and other methods are used for measuring.
In one of the first issues of the journal Kart og Plan, Map and Plan, Lars Loe has an article where measurements from the platform on Urbygningen are used. Students and staff climbed to the top of the roof and took their measurements in all kinds of weather.
Tårnbygningen was started 20 years after the Urbygningen was put into use. In this project, a measuring point was planned that was less exposed to the weather and was a safer area. Sources indicate that it was cold in the Tower during winter because the windows had to be opened for measurements, as the glass refracts the light.
The tower room was equipped with a double floor. There were iron bowls embedded in the lower floor that went through to the upper floor. This was to ensure that the stands could be securely fastened to the lower floor when measurements were carried out.
The purpose of the two floors was to allow movement on the upper floor without affecting the floor below. The bowls and instruments had to remain completely still. In the middle of the floor in the tower room, there is a screw. It is placed centrally under the sphere. It was used as a reference point for measurements from the tower room.
Students aimed through open windows and out to trigonometric points. From the tower room, there was a good view, especially to the west. It was possible to see the signals on triangulation points on the other side of the Oslofjord. Such signals were usually placed at the top of wooden towers, marked with red and white at the top.
The university thus has a building that is physically designed for surveying. This is relatively unique.
The sphere in the spire of the Tårnbygningen was a “triangulation point NMBU” in the National Mapping Authority’s fixed point register. The center of this sphere was an NGA point (Norwegian Geographical Survey), registered with the original coordinates.
The same was true for the tower at Ås Church.
Network of Surveying Points on Campus
Inge Revhaug has extensive experience and good knowledge of the history of surveying. He can tell that the Department of Surveying was located on the 3rd floor of the Tårnbygningen and had a relatively short distance to the tower room.
According to him, Aarstein Waade mentioned that the tower room was used as the first point in a network of surveying points on campus.
To establish the first points in the network, angles were measured with a theodolite and distances with an electro-optical distance meter. It must have been a Geodimeter, the world’s first electro-optical distance meter developed by Bergstrand in Sweden in the 1940s. It was a relatively large box. A light bulb sent light into a Kerr cell, a container filled with benzene and two electrodes, which modulated the light. A prism reflected the light back. The measurements were performed manually to get the reflected signal to align with the wave being sent out. The institute had a Geodimeter model 4.
Concrete Pillars From Recent Times
Inge mentions that there is a concrete pillar on open rock towards the greenhouses. It was cast by Arild Veidal over a bolt used by Olav Mathisen. It was precisely measured in relation to the AK06 pillar on the roof of Sørhellinga (built in 1980). The AK points consisted of a network of points, where the coordinates were measured by GPS. The measurements were carried out continuously over several days, and the calculation of the coordinates was done with special software. The pillar was used as a starting point for polygonal chains and static measurements with a satellite receiver.
There are 6 pillars in a row from Gullberg to Norderås. (Gullberg is the name of the first house in Syverudveien.) It was a calibration base. The distance between the pillars was measured with a Mekometer, the world’s most accurate distance meter. The precision is 0.25 millimeters. Bases are used to control and adjust electro-optical distance meters.
Anecdote
"When we were children, the bravest of us ran across the ridge of Urbygningen.” This is something the writer has personally heard from one of those who grew up in the houses in the park.
Fortunately, someone discovered this, and the door to the platform in Urbygningen was locked. Now, the platform is only accessed when changing flags and pennants.
