- A magnetic Habsburg eagle. The Latin inscription around the eagle’s feet “Et Boreae et Austri-acus” is a play on words linking the compass needle (“the needle of both North and South” to the house of Austria (“Austriacus”). Detail from Athanasius Kircher, Magnes (1654 edn.) Sig. †3 verso. Courtesy of Stanford University Libraries. Click on the image for an enlargement.