Letter, regarding 'On the secular changes of the magnetic system of the Earth' from Christopher Hansteen to the Royal Society Hansteen introduces a paper he has written regarding ascertaining the movement of the four magnetic polar regions. He expresses gratitude to 'English science' for providing him with materials and observations to use in his research. Annotations in pencil throughout. Subject: Magnetism Written by Hansteen at Christiania Observatory [Oslo]. This letter was published in full in volume 8 of the Proceedings of the Royal Society as 'The following letter was read, from Professor Hansteen of Christiania, For. Mem. R. S'. 31 December 1855