A magnetic compass resting on an Ordnance Survey map. The magnetic compass,an instrument for finding direction,consists of a thin piece of magnetic material with the north-seeking pole indicated,free to rotate on a pivot and mounted on a compass card on which the points of the compass are marked. The needle becomes aligned to the local component of the Earth's magnetic field,resting north to south. True north can then be found from tables of magnetic corrections | |
Licence : | Droits gérés |
Crédit: | Science Photo Library / Hart-Davis, Adrienne |
Taille de l’image : | 3233 px × 4002 px |
Model Release : | Non requis |
Property Release : | Non requis |
Restrictions : | - |