The first geomagnetic map of the Adriatic by Karl Kreil and the "Lloyd's Libra" a historical variometer

Melichar, P.

Central Institute for Meteorology and Geomagnetism


The first geomagnetic map of the Adriatic by Karl Kreil


In this historical nautical chart of the Adriatic Sea of ​​1825 there are in addition to the usual geographical indications of length and latitude special entries. These are exact sea depths and information about the harbor entrances. For navigation, course lines are drawn. These are connecting lines of striking coastal points to support navigation in the open sea. In larger ports the declination measured by Karl Kreil was registered. In this map, the main direction of the Adriatic is called "Maestro" - today this is the direction north-west. As an example, the declination of Venice in the original text: "Decl. magn. a Venezia nel 1854 14º 34 'a Maestro "Today one would say: Western Declination 14º 34' from Venice referring to 1854". On July 23, 1851, the "k.k. Central Institute for Meteorology and Earth Magnetism ", Kreil became its first director and at the same time full professor of physics at the University of Vienna. Kreil carried out the first geomagnetic land survey from 1843 to 1858 in the countries of the Austro-Hungarian Monarchy, the Adriatic and in some neighboring countries. One of his field instruments was the "Inclinatorium" by John Dover from London with the serial number 1 and the "Unifilar" by Moritz Leyser from Leipzig for measuring the declination. Karl Kreil was a member of the Magnetic Association in Göttingen (1836-1841) founded by Carl Friedrich Gauss. Letters from Gauss to Kreil with travel documents provide insights into historical land surveying.


The "Lloyd's Libra" a historical variometer of the Central Institute for Meteorology and Geomagnetism in Vienna


This instrument for observing the variations of the vertical component of the geomagnetic field was used in the "First International Polar Year 1882/83" on the island of Jan Mayen in the Arctic Observatory of the Austro-Hungarian Polar Expedition. It was designed and built by Prof. Max Thomas Edelmann, physicist and engineer in Munich, together with Prof. Heinrich Iwanowitsch Wild, meteorologist and physicist in Zurich around 1880 in the physico-mechanical institute.