EVIDENCE FOR CHURCH ORIENTATION BY MAGNETIC COMPASS IN TWELFTH‐CENTURY DENMARK

Abstract

The orientations of some 570 Romanesque churches (one‐third of the total) from four regions in Denmark show significant differences in the claimed east‐west orientation, being typically rotated 5‐15° clockwise from true east‐west. Magnetic declination was predominantly easterly between AD 1000 and 1600; the church deviations probably originate from sometimes using a magnetic compass, other simple and plausible causes for this ‘skewness’, for example orientation by the sun at specific periods of the year or astronomical alignment, being hard to design. Hence, some 25% of the churches were probably oriented by means of a magnetic compass. As a tool for dating, the orientations have not yet been successful due to statistical scatter.Church building in Denmark boomed in the twelfth century. The early history of the compass is somewhat uncertain. The first European reference known is from about 1190‐1200, while the oldest Norse source is from about 1225 (Landnámabók), saying that the lodestone was not known before. Danish churches thus bring new information about the early use of the magnetic compass in Europe.