Iron pole Lommel

This iron pole is actually a removable cast iron bell jar.

The bell jar served to cover the bluestone stone that served as support for the optical instrument used to measure the geodetic point in 1855. In that summer , nightly astronomical observations were made for months at the Station Géodésique in the Pijnven to determine the position against the stars to determine latitude and azimuth.

In retrospect, the optical instrument used turned out not to be entirely suitable for the intended precision of the positioning and the observations and calculations were repeated in 1886.

The Geodetic Base of Lommel is a line between several measurement points, the distance of which was accurately determined in 1852 as the starting point for making a new topographical map of Belgium. This is based on a triangulation: a triangular network of measured geodesic points whose location and distance to each other is determined by trigonometry.

To measure the distance between those points, one starts from a geodesic basis with two or more points, the distance of which has been measured as accurately as possible. By using optical instruments and the property of triangles that if the length of 1 side and the size of the adjacent angles is known (the sine rule), the length of the other two sides can be calculated from this . In this way, the distance to other points and their location can be determined. This allows the terrain to be mapped correctly.

Willem Vandenameele